The head of a high-profile probe of CIA prisons in Europe accused the US administration of “gangster-style methods” on Tuesday but failed to produce hard evidence that European governments had hosted any such facilities.

Dick Marty, the Swiss politician looking into the case for the Council of Europe, the 46-nation human rights organisation, said in an interim report that US renditions, or extra-legal abductions, had challenged “the very foundation of the law-based state and its democratic foundation”.