A top official from the Council of Europe - the continent's human rights watchdog - lashed out at Poland, Romania and Lithuania on Monday over their failure to come clean on their involvement in CIA secret renditions, DPA reported.
In the aftermath of the September 11, 2001 attacks by al-Qaeda, the US intelligence services started a worldwide programme to kidnap and torture suspected terrorists, holding them in secret prisons.
Three of these CIA "black sites" have been found out to have been hosted by Poland, Romania and Lithuania.
The three countries "extended quite extraordinary permissions and protections to their American partners - while respecting conditions of total secrecy," the Council of Europe's Commissioner for Human Rights, Thomas Hammarberg, wrote on his website.
"The full truth must now be established and guarantees given that such forms of co-operation will never be repeated," he added. Investigations over what happened have been launched in Poland and Lithuania, while no action has been taken in Romania.
"The purported cost to transatlantic relations of pursuing such accountability cannot be compared to the damage inflicted on our European system of human rights protection by allowing ourselves to be kept in the dark," Hammarberg charged.
Hammarberg's warning came in the week leading to the 10th anniversary of the September 11 attacks, which is reigniting debate on the repercussions they and the US response to them had on the world.