The US Congress promised on Thursday to look more closely at the practice of “extraordinary renditions”, one of the more controversial tools used by the Central Intelligence Agency in fighting terrorism.

The Bush administration has been heavily criticised over the Abu Ghraib scandal and the US military prison at Guantánamo Bay, Cuba. But Capitol Hill has hitherto paid little attention to renditions, the programme under which the CIA sends terrorist suspects to secret prisons, or to foreign governments that sometimes have a record of torturing prisoners, for interrogation.