Updated

At first, in her desperate calls home to her mother in Pakistan, Natasha Masih couldn't bring herself to say what they were doing to her.

All the 19-year-old would say was that her new husband — a Chinese man her family sold her off to in marriage — was torturing her. Eventually she broke down and told her mother the full story, pleading with her to bring her home. The husband had hidden her away in a hotel in a remote corner of China and for the past weeks had been forcing her to have sex with other men.

"I bought you in Pakistan," she said her husband told her. "You belong to me. You are my property."

Her mother turned to the only people she knew who could help, her small evangelical church in a run-down slum of the Pakistani city of Faisalabad. There, a group of parishioners began putting together an elaborate plan to rescue the girl from the hotel more than 1,100 miles away.

Natasha was one of hundreds of Pakistani girls who have been married off to Chinese men in return for cash payments to their families, most of them Christians, a community that is among the poorest of the poor in the country. The Associated Press reported previously how Christian pastors and Pakistani and Chinese brokers work together in a lucrative trade, aggressively pursuing Pakistani girls who are tricked into fraudulent marriages and find themselves trapped in China with sometimes abusive husbands.

Since then, police investigations have uncovered that many of the women are forced into prostitution in China. A picture of the extent of the trafficking networks has emerged from a series of arrests and raids in recent weeks by Pakistan's Federal Investigation Agency, as well as testimony from victims, many of whom were previously too frightened to come forward.

The AP spoke to seven girls who had been forced into prostitution — four of them still in China.

Families are told their daughters will be wed to well-off businessmen and given good lives in China, and the marriage trade is depicted as a benefit for all sides — impoverished parents receive money, while Chinese men find brides in a country where men outnumber women. But investigators are increasingly convinced that the majority of the girls are sold into prostitution, two law enforcement officials familiar with the investigations told the AP.

"The girls who are interviewed say they were tortured" — using a euphemism for rape and forced prostitution, said one of the officials. "They are afraid for their families and for the disgust they fear they will feel. ... Make no mistake, this is trafficking."

However, even as investigators are uncovering the scope of the trade, the Pakistani government has sought to keep it quiet. Senior government officials have ordered investigators to remain silent about the trafficking because they don't want to jeopardize Pakistan's increasingly close economic relationship with China, the two officials said, speaking on condition of anonymity for that reason.

Beijing is investing billions of dollars in Pakistan as part of its Belt and Road Initiative, a global endeavor aimed at reconstituting the Silk Road and linking China to all corners of Asia. Under a $75 billion project known as the China-Pakistan Economic Corridor, Beijing has promised a sprawling package of infrastructure development, from road construction and power plants to agriculture. The largest component is a 3,200-kilometer (2,000-mile) road linking China to Pakistan's deep-water port of Gwadar on the Arabian Sea.

In Pakistan, it has been billed as a massive development program that will bring new prosperity to the South Asian nation, where the average citizen lives on just $125 a month. Since 2015, thousands of Chinese have arrived in Pakistan to work on a multitude of projects.

China's ambassador to Pakistan has gone on local television channels denying girls are trafficked to China and sold into prostitution. The issue of human trafficking was not discussed during a visit to Pakistan this month by China's vice president, Wang Qishan, who held talks with Prime Minister Imran Khan and Pakistan's president. In comments carried in the Pakistani press, Wang denied trafficking was taking place — and referred to an online video that traffickers often use to lure in families, showing Pakistani brides in China dancing and happy.

"China is denying it is happening, but we are showing the proof," said Saleem Iqbal, an activist in Pakistan's small Christian minority who has helped bring girls back from China and collects evidence of trafficking networks that he provides to police.

The AP spoke by messaging app with Arooj, a Pakistani girl still trapped in China. She said her husband beat her and would come home drunk with friends and force her to have sex with them. Like many of the girls, she wasn't sure where she was in China; often they are taken from Beijing on flights elsewhere in the country, then driven for hours to small towns, without being told the destination.

Ijaz Alam Augustine, the human rights and minorities minister in Pakistan's Punjab province, estimated that more than 500 women have been trafficked to China, while Iqbal put the figure at 750 to 1,000.

In early May, Pakistani police swept through posh neighborhoods in the Punjab provincial capital of Lahore and in the national capital, Islamabad. They arrested Chinese nationals and their Pakistani partners involved in two marriage-broker networks that sought out Pakistani girls for Chinese grooms. They all now face trafficking charges.

Investigators have since made further arrests in smaller Punjab towns and in the western city of Peshawar, rolling up more networks. Overall, at least two dozen Chinese and dozens of Pakistanis have been arrested.

The two law enforcement officials said the Lahore-based network had been operating for at least a year. The network was protected by corrupt policemen, and the son of a former senior police official served as the lynchpin between the Chinese and Pakistani operatives, the officials said.

The network also benefited from lax oversight by authorities, they said. For example, at least five of the Chinese traffickers were able to enter Pakistan on business visas based on companies that didn't exist.

The AP saw one of the charge sheets from the wave of arrests, in which eight Chinese nationals and five Pakistanis were charged with human trafficking. It also accused the traffickers of profiting on body parts stolen from girls trafficked to China, without offering evidence. Other police reports tell of a Pakistani pastor who signed dozens of empty marriage certificates, which were later filled out by traffickers once they had acquired a prospective bride.

Investigators have conducted dozens of interviews in recent weeks with trafficked girls and women, who are increasingly speaking out.

One woman, Sumaira, who was sold to a Chinese groom by her brothers, told the AP she had remained silent for months after escaping her husband, even refusing to talk to investigators. But now she is coming forward.

"If I had told everything that happened to me then, maybe I would have saved so many other Pakistani girls," she said. "But I was too afraid, too afraid of my brothers. Now I want the people that did this to me to not do it to other girls."

The 30-year-old Sumaira had been running a small beauty salon in a poor, mostly Christian neighborhood of the Punjab town of Gujranwala. "I was a very different person than what you see now," she said. "Then I had hope. I believed in my future. Now I don't know."

Her brothers forced her to marry in July last year after being offered money by brokers. Her husband took her first to a house in Islamabad, where she said she was kept for a week, raped every night by Chinese men.

Before leaving for China, she convinced her husband to let her go home to say farewell to her sisters.

"When I got home, I yelled at my brothers, 'Why did you sell me? How much money did you get for me?'" she said. The brothers beat her, but she managed to escape to the home of an uncle.

Natasha Masih lives in Wasirpura, a mainly Christian district of Faisalabad where many work as domestic workers. She didn't want to marry, but "what could I do, my family is poor." A friend of her father suggested he marry her to a Chinese man. She said her father struggled with the decision but needed the money. He had four other daughters and could no longer work after hurting his back. Natasha said refusing was never an option.

In November, her husband took her to China's remote northwestern region. She was driven to a forested area and a small house with no kitchen or bathroom that she was told would be her home. She discovered that three male and two female friends of her husband shared the house. Soon, her husband began to force her to have sex with the men.

Soon after, her husband took her to the Yin Du luxury hotel in the nearby city of Urumqi. There, he confined her to a room and sold her into prostitution.

"Always two or three men were the same, and then he would bring other men, ordering me to have sex with them," she said. "I was living in hell-like conditions, silently weeping, silently praying for help." She made furtive calls to her parents on her mobile phone.

Back in Faisalabad, a member of her parent's church, Farooq Masih, formed a group of men from the congregation to try to help. Masih, who is not related to Natasha, told the AP they struggled with how to free Natasha until one among them told of his younger brother who was a student in China. The brother agreed to contact Natasha's husband, pose as a client and pay him to sleep with her to get access to her.

The student texted Natasha and told her he was coming to rescue her, asking for details of when her husband comes and goes from the hotel. Finally, the day came. He called her and told her to slip outside the hotel to where he was waiting in a taxi.

"I saw him and quickly I took my clothes and got into his taxi," she said. "I didn't ask his name. I didn't ask anything, I just said, 'Brother, thank you.'" Soon she was on a plane to Pakistan.

Farooq Masih and the other men from the church have since dedicated hours to unearthing trafficking networks. They recently conducted their own sting operation in Faisalabad, orchestrating a fake marriage to a prospective Chinese groom that led the Federal Investigation Agency to the Chinese and Pakistani brokers and the pastor who solemnized the unions for a fee.

Meanwhile, Natasha — who turned 20 last week — helps other young women open up about their experiences and encourages them to talk to investigators. She has heard reports that her husband was back in Pakistan looking for another girl to marry.

"I am lucky," Natasha said. "Many girls who were taken there by their husbands are still living a terrible life. ... Now I know what is freedom and what is slavery. In China, I was treated as a slave by my husband."