Geoff Hoon, the minister for Europe, has been attacked by an international delegation of European MPs for evading questions about claims that Britain co-operated with CIA torture flights across Europe.
The MEPs accused the Government of breaking international law by failing to investigate claims that Britain was used for "extraordinary rendition" flights taking suspects to secret jails and countries which used torture.
They criticised Mr Hoon for failing to answer detailed questions about allegations that nearly 200 flights stopped off in Britain during their secret missions.
The nine-strong delegation from the European Parliament accused Mr Hoon of being evasive when asked whether the Government knew of the flights, branding him one of the least helpful ministers they have interviewed during their investigation.
The leader of the delegation, the Liberal Democrat MEP Baroness Ludford, said: "We felt his answers were not as forthcoming or informative as would be justified by the weight of the allegations raised in the various parliamentary fora. I think we felt there was an unwillingness to engage with the questions.
"It's not enough to say there's nothing to look at. The allegations are credible enough to trigger an obligation to investigate. The meetings have highlighted the need to investigate allegations concerning the involvement of UK intelligence services personnel in rendition operations against British victims and the possible holding of terrorist suspects in an air base in Germany."
Claudio Fava, the official rapporteur for the committee, said they found evidence of 172 CIA flights that used UK airports, but said Mr Hoon had provided no information about whether the Government knew of the operations.
He said: "His replies were somewhat evasive in particular regarding the flights by the CIA or by companies run by the CIA."
Mr Fava, an Italian MEP who will table a draft report to the committee next month, said the meeting with Mr Hoon "proved to be the least fruitful of any meeting with ministers in recent months".
The MEPs had spent two days in London meeting senior MPs and human rights groups, as well as relatives and lawyers of three alleged victims.
Amnesty International has condemned the British Government's for adopting an approach of "see no evil, hear no evil" towards rendition flights.
Last month, for the first time, President George Bush acknowledged that secret CIA prisons existed.Reuse content