By Ilyas Khan
BBC News, Karachi
A human rights watchdog in Pakistan says it has identified 200 cases of "missing" people who it believes are in the custody of the security agencies.
Hundreds of Pakistanis have disappeared since 2001
The Human Rights Commission of Pakistan said it would file a court petition next week to seek their recovery.
Human rights organisations say more than 1,000 people are reported to have gone missing since 2001.
Pakistan's courts have rejected hundreds of petitions to free them after officials denied holding them.
But in a recent case the Supreme Court forced the government to acknowledge custody of at least 25 such persons.
Many of those released from custody have alleged that they were held by military intelligence agencies.
In many cases, relatives of the missing persons have claimed that they were told by the security agencies not to worry as their family members would soon be freed.
The HRCP recently investigated and recorded 241 cases of such "enforced disappearances", half of them nationalists from the insurgency-hit province of Balochistan.
Their relatives allege they are being held either by the Inter-Services Intelligence (ISI) agency or Military Intelligence (MI).
Government officials invariably deny such allegations.
Last September, human rights organisation Amnesty International criticised Pakistani intelligence officials. It said they were abducting people with little or no proof of al-Qaeda connections and selling them to the US.
But the HRCP says the vast majority of illegally detained persons are linked to nationalist parties in Sindh and Balochistan provinces.
Both provinces are home to strong opposition to the military government of General Musharraf, and an armed insurgency has kept Balochistan volatile.
"Most of the 200 persons listed in our petition hail from Balochistan and Sindh," says Iqbal Haider, an HRCP official.
The HRCP chairperson, Asma Jehangir, said the missing persons also included women.
"Some of the women reached the HRCP office and narrated their tale of wrongful confinement and how they were taken to the military headquarters [in Rawalpindi] for interrogation," she said.
At least one woman suspected by the US of having links to al-Qaeda, Dr Afia Siddiqui, has been missing since 2003 along with her three children.