Those released are among nearly 500 men presumed to have disappeared into the hands of the Pakistani secret agencies cooperating with Washington’s fight against terrorism since 2001, the report quoted human rights groups and lawyers in Islamabad as saying.

Pakistan’s intelligence agencies, which are apparently trying to avoid acknowledging an elaborate secret detention system, warned detainees not to speak to anyone about their detention. However, fragments of their experiences have filtered out through relatives and their lawyers, the report said.

No official reason has been given for the releases, but as pressure has mounted to bring the cases into the courts, the government has decided to jettison some suspects and spare itself the embarrassment of having to reveal that people have been held on flimsy evidence in the secret system, the New York Times reported. A few even appeared in court and told their stories, and it became increasingly clear that the “disappeared” men had in fact been held in military or intelligence agency cells around the country, often for several years without being charged.

In one case, a suspect tried to, but not charged with the 2002 killing of Daniel Pearl, the American journalist, was dumped on a garbage heap, he died 20 days later.

He, like one other detainee, was arrested in South Africa several years ago and released in Pakistan this year, it said.