Key Pakistani institutions have snubbed a United Nations team invited by the government to investigate thousands of people who were allegedly detained by law enforcement and intelligence agencies and are said to be still missing.

The group pressed the government and judiciary to do more tackle the problem of missing persons as it ended a 10-day research trip Thursday. But the lack of cooperation it received raises questions about how much impact the visit will have. The Supreme Court, military and main spy agency refused to meet the group.

The visit was also clouded by complaints from lawmakers who claimed the group's presence was a violation of the country's sovereignty.

"Relatives of the disappeared persons have the right to the truth, the right to justice and the right to reparation," one of the working group members, Olivier de Frouville, said during a press conference in Islamabad. "It is the duty of the state of Pakistan to take all necessary measures to make those rights effective."

Pakistani human rights organizations have long accused law enforcement and intelligence agencies of snatching citizens and holding them without charges or killing them and dumping their bodies, allegations officials have denied. The number of cases spiked over the past decade as Pakistan partnered with the U.S. to fight al-Qaida and also battled domestic insurgencies by the Taliban and separatist groups in southwest Baluchistan province.

Some claim that 14,000 people are still missing in Baluchistan alone, although the provincial government recognizes less than 100, said de Frouville. Political and human rights activists have also allegedly been targeted, he said.

The group met with a variety of judicial and government officials, including Interior Minister Rehman Malik and Foreign Minister Hina Rabbani Khar. It also met with NGO representatives, lawyers and relatives of victims.

Most of the relatives who spoke to the U.N. blamed law enforcement and intelligence agencies for taking their loved ones, said de Frouville. Many claimed they were threatened by officials when they tried to register cases or testify, he said.

Some government officials who spoke to the group downplayed the number of people missing, saying many of them were criminals in hiding, had joined militant groups or had been abducted by non-state actors, said de Frouville.

The U.N. welcomed steps taken by the government and the Supreme Court to set up commissions to investigate missing person cases, but relatives of victims complained that many of the cases remain unsolved and alleged perpetrators are rarely convicted, said de Frouville.

"The working group, despite its repeated requests, has received no information related to convictions of state agents in relation to acts of enforced disappearances," said de Frouville.

He concluded his statements by recounting a conversation he had during his visit with a victim's mother, who said, "If your child disappeared, what would you do?"

"This question summarizes the ordeal families are going through," said de Frouville.