A liberal Pakistani activist who went missing earlier this year has said a "government institution" with links to the military held him and tortured him.
Waqass Goraya, one of five activists who disappeared in early January, told the BBC he was tortured "for pleasure".
The activists were freed after several weeks - but until now none of them has said who was behind their mistreatment.
Pakistan's army has previously denied any involvement in the case. There were vocal protests seeking their release.
Pakistan is one of the the world's most dangerous countries for reporters and human rights activists, and critics of the powerful military have been detained, beaten or killed.
Waqass Goraya - who now lives in the Netherlands - told the BBC he had been tortured "beyond limits".
He described being punched, slapped and forced into stress positions during the three weeks he was held. He worried he would never be released.
"We knew it was over… We will die under torture," he told the BBC.
He also spoke at a side event at the United Nations Human Rights Council in Geneva about his experiences.
Mr Goraya believes he was detained because he ran a satirical Facebook page critical of the influence of the Pakistani military in the country's political system.
The page has also criticised military policy in Pakistan's restive Balochistan province. Mr Goraya strongly denies breaking any laws.
"I hadn't done anything criminal - otherwise I would've been in a court not in illegal detention," he told the BBC.
At a press conference in January, a spokesman for Pakistan's powerful military said it had had nothing to do with the disappearance of the bloggers.
Pakistan's interior minister had previously said the government did not tolerate "enforced disappearances".
After Waqass Goraya and the other activists disappeared, a campaign demanding their release sprang up around the hashtag #recoverallactivists. But a counter-campaign both online - and backed by a number of TV anchors - accusing them of blasphemy also began.
Blasphemy is an emotive issue in Pakistan - and can legally be punishable by death.
Mr Goraya says the allegations of blasphemy are false, and that alleged blasphemous postings have been fabricated.
Following a court petition by an Islamist leader, on 8 March legal proceedings were begun calling for the prosecution of those behind a number of social media pages allegedly run by the missing activists.
All of them are now believed to be outside Pakistan. Pakistan's Interior Minister Chaudhry Nisar Ali Khan has previously raised concern about the blasphemy allegations against the activists - but following the court ruling threatened to block "all social media websites" that had blasphemous content.
Mr Goraya believes the blasphemy allegations are an attempt "to shut us down - to threaten our families - to build pressure on us".
A protest was held in Islamabad on 8 March by religious groups calling for action against the activists and criticising the government for letting them leave the country.
Mr Goraya says he believes that by speaking to the UN, he can help build pressure in Pakistan to pass a bill currently before parliament that would force the security services to provide information on a "missing person" in their detention within three days of a request.
He also wants accountability for what happened to him.
"The government should investigate it. We have evidence - strong evidence - it will directly lead to the persons responsible."
Mr Goraya still has nerve damage in his hands and feet, as well as problems with his hearing - but says he is determined to continue activist work.
"They are still picking people, more and more people are being harmed - our friends, our colleagues - so how can we stop? Someone has to stand up."