London ? In its most detailed report yet on alleged secret rendition flights of terror suspects, Amnesty International said three former detainees have lent support to the idea that eastern European countries may have been involved in secret CIA flights to so-called “black site” prisons.

The report provides detailed accounts of the experiences of three Yemeni men – Muhammad Bashmilah, Muhammad al-Assad and Salah Nasser Salim Ali – who believe they were taken by U.S. authorities to secret prisons following lengthy journeys through different climates and time zones.

Bashmilah said he was detained in Jordan in October 2003 while on a trip to visit his mother. Ali said he was detained in Indonesia in August 2003 and then flown to Jordan where he was taken into custody. Al-Assad said he was detained in Tanzania in 2003. None of the three could say with confidence where they were taken next.

In statements from February and March, they described travel times, changing climates, temperatures and daylight hours in detailed descriptions Amnesty says indicates they may have been held in eastern Europe.

The men were allegedly held for 13 months at a so-called “black site,” a clandestine facility believed to be run by the CIA, before they were returned to Yemen where they were charged with forging travel documents, Amnesty said.

In a statement released with the report, Amnesty International said new information from the men raised “the possibility that they were held somewhere in eastern Europe or central Asia.”

“Their captors went to great lengths to conceal their location from the men, but circumstantial evidence such as climate, prayer schedules and flight times to and from the site suggest that they may have been held in eastern Europe or central Asia,” Anne FitzGerald, a senior advisor with Amnesty, said in the statement. “But without further information from the U.S. government and European authorities, it’s impossible to verify exactly where.”

The CIA declined to comment on the report, but the U.S government has said that renditions are carried out according to U.S. law and with its obligations under international law.

The Council of Europe, the continent’s top human rights watchdog, called for a probe into the secret prisons. Its report, released last month, did not produce any evidence of secret prisons on European territory.

The Amnesty report also said the CIA is exploiting a loophole that allows private aircraft to land at foreign airports without having to inform local authorities – unlike government or military planes – and called for inspections of planes suspected of being involved in renditions.