An Indian man freed after spending 35 years in Pakistani prisons for espionage has admitted being a spy, leading the Pakistani minister who organized the release to say it would now be harder to free other prisoners.

"I did the duty assigned to me as a spy ... I was a regular recruit," Kashmir Singh told reporters Friday. "I did not open my mouth for 35 years in Pakistan."

The Pakistani minister who was instrumental in freeing Singh, who was released Tuesday, said he did not know he was a spy. During his trial in the 1970s, Singh had repeatedly denied he was an agent for Indian military intelligence.

His unconditional release was partly meant to reduce the deep-rooted enmity between the South Asian rivals, who have detained many of each other's citizens.

"I am shocked to hear these statements," Pakistan Minister for Human Rights Ansar Burney told CNN-IBN, a private TV news channel in India. "It will surely make it difficult for Indian prisoners in Pakistan and Pakistani prisoners in India."

Burney said he worked to free Singh "on humanitarian grounds for a man who was in jail" for 35 years, adding he still planned to work to free other Pakistani and Indian prisoners.

Singh received a hero's welcome when he walked across the border Tuesday and was greeted by his wife bearing flowers and sweets. The former policeman apparently decided to speak out after finding his wife and son living in poverty, not cared for by Indian authorities.

"The government after my arrest did not bother to spend a single penny for my family," he said.

Telephone calls to the Indian military were not immediately returned on Saturday.

In a news conference Friday in the northern city of Chandigarh, Singh described the lengths he went to live undetected in Pakistan, including getting circumcised so he could pass as a Muslim, studying Urdu and adopting the name Ibrahim.

While in Pakistan, he ate beef, which is forbidden in his Sikh religion, and fasted during the Muslim holy month of Ramadan.

Singh was arrested in 1973 in the Pakistani city of Rawalpindi. His cover story was that he was a trader in electronic goods traveling on business.

Singh was convicted of spying and sentenced to death by a military court despite repeated denials that he was a spy. The government commuted Singh's execution in the late 1970s but the case languished.

Burney learned of Singh in December and began working for his release, finally persuading President Pervez Musharraf to grant clemency.

The two countries have arrested many of each other's citizens, including fishermen and others who say they accidentally strayed across the border. Some are imprisoned for years on espionage charges, usually with no contact with their families.

India says there are some 600 other Indian prisoners in Pakistani jails. Pakistan said there are some 200 of its nationals in Indian jails.