ISLAMABAD, Pakistan -- On Sept. 6, 2006, President Bush announced that the CIA's overseas secret prisons had been temporarily emptied and 14 al-Qaeda leaders taken to Guantanamo Bay, Cuba. But since then, there has been no official accounting of what happened to about 30 other "ghost prisoners" who spent extended time in the custody of the CIA.

Some have been secretly transferred to their home countries, where they remain in detention and out of public view, according to interviews in Pakistan and Europe with government officials, human rights groups and lawyers for the detainees. Others have disappeared without a trace and may or may not still be under CIA control.

The bulk of the ghost prisoners were captured in Pakistan, where they scattered after the U.S. invasion of Afghanistan in 2001.

Among them is Mustafa Setmariam Nasar, a dual citizen of Syria and Spain and an influential al-Qaeda ideologue who was last seen two years ago. On Oct. 31, 2005, the red-bearded radical with a $5 million U.S. bounty on his head arrived in the Pakistani border city of Quetta, unaware he was being followed.

Nasar was cornered by police as he and a small group of followers stopped for dinner. Soon after, according to Pakistani officials, he was handed over to U.S. spies and vanished into the CIA's prison network. Since then, various reports have placed him in Syria, Afghanistan and India, though nobody has been able to confirm his whereabouts.

Nearly all the Arab members of al-Qaeda caught in Pakistan were given to the CIA, Pakistani security officials said. But the fate of several Pakistani al-Qaeda operatives who were also captured remains murky; the Pakistani government has ignored a number of lawsuits filed by relatives seeking information.

"You just don't know -- either these people are in the custody of the Pakistanis or the Americans," said Zafarullah Khan, human rights coordinator for the Pakistan Muslim League, an opposition political party.

Others have been handed over to governments that have kept their presence a secret.

Since 2004, for example, the CIA has handed five Libyan fighters to authorities in Tripoli. Two had been covertly nabbed by the CIA in China and Thailand, while the others were caught in Pakistan and held in CIA prisons in Afghanistan, Eastern Europe and other locations, according to Libyan sources.

The Libyan government has kept silent about the cases. But Libyan political exiles said the men are kept in isolation with no prospect of an open trial.

Other ghost prisoners are believed to remain in U.S. custody after passing into and out of the CIA's hands, according to human rights groups.

Relatives of a Tunisian al-Qaeda suspect known as Retha al-Tunisi, captured in Karachi, Pakistan, in 2002, received notice recently from the International Committee of the Red Cross that he is detained at a U.S. military prison in Afghanistan, said Clara Gutteridge, an investigator for Reprieve, a London-based legal rights group that represents many inmates at the U.S. prison at Guantanamo Bay. Other prisoners, since released, had previously reported seeing Tunisi at a secret CIA "black site" in Afghanistan.