The Soviet-era compound is part of a network that has included sites in eight countries, including Thailand and Afghanistan, the newspaper reported, citing US and foreign officials familiar with the arrangement.

The newspaper said the existence and locations of the facilities are known only to a handful of officials in the United States and, usually, only to the president and a few top intelligence officers in each host country.

The CIA has not acknowledged the existence of a secret prison network, the Post said. A CIA spokesman did not immediately return a call seeking comment.

The prisons are referred to as "black sites" in classified US documents and virtually nothing is known about who the detainees are, how they are interrogated or about decisions on how long they will be held, the report said.

About 30 major terrorism suspects have been held at black sites while more than 70 other detainees, considered less important, were delivered to foreign intelligence services under a process known as "rendition," the paper said, citing US and foreign intelligence sources.

The top 30 al-Qaeda prisoners are isolated from the outside world, they have no recognized legal rights and no one outside the CIA is allowed to talk with or see them, the sources told the newspaper.

The paper, citing several former and current intelligence and other US government officials, said the CIA used such detention centres abroad because in the United States it is illegal to hold prisoners in such isolation.