The High Court in London has been hearing claims that Foreign Office officials actively supported sending British terror suspects to the American detention camp at Guantanamo Bay in Cuba after the terrorist attacks on September 11 2001.
Documents have been revealed in the High Court as part of a legal action by six men who claim the UK government, including MI5 and MI6, failed to stop their detention or were complicit in it.
The papers show Foreign Office officials suggested the US facility would be the "best way" to deal with suspects held in Afghanistan in the immediate wake of the September 11 attacks, the BBC reports.
The court has also heard claims that former Prime Minister Tony Blair's office frustrated attempts by consular officials to help a detainee who was facing transfer to Guantanamo Bay.
At least 60 government lawyers and officials are working on the case, which could run for years. They are working in a secure location, sifting through 500,000 sensitive documents, many handed over by MI5 and MI6.
Britain's current coalition government last week announced an inquiry into the treatment of detainees.