The former head of MI5 has claimed US intelligence agencies "concealed²" their mistreatment of terror suspects.

英国军情五处前首脑宣称，美国情报机构故意“掩盖”他们虐待恐怖主义嫌疑犯的行为。

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Baroness Mannigham-Buller spoke at a lecture in the House of Lords

Baroness Eliza Manningham-Buller said she only discovered alleged⁵ 9/11 mastermind（策划者，才子） Khalid Sheikh Mohammed was waterboarded after retiring in 2007.

In a lecture at the House of Lords, she said the US had been "very keen to conceal¹（隐藏，隐瞒） from us what was happening".

Her comments follow controversy⁶ over UK agents' alleged collusion（共谋，勾结） with US counterparts using torture techniques.

Last month it emerged that Binyam Mohamed, a British resident formerly⁷ held at Guantanamo Bay, had been subjected to "cruel, inhuman⁸ and degrading（不名誉的，可耻的） " treatment.

Ministers and current MI5 head Jonathan Evans have insisted that there was no collusion by UK security officers.

However, questions remain about exactly when they learnt that the US apparently⁹ changed its rules on torture after the 9/11 attacks.

Lady Manningham-Buller, who headed MI5 between 2002 and 2007, said: "The Americans were very keen that people like us did not discover what they were doing."

In a lecture at an event organised by the Mile End Group, she said she had wondered, in 2002 and 2003, how the US had been able to supply the UK with intelligence from Mohamed and was told that he was "very proud of his achievements when questioned about it".

"It wasn't actually until after I retired¹⁰ that I read that, in fact, he had been waterboarded 160 times," she said.

Lady Manningham-Buller said the government had lodged¹¹ "protests" with the US about its treatment of detainees（被扣押者） , but refused to go into further detail.

A Foreign Office spokeswoman was not prepared to comment on the former MI5 chief's comments.

She said the Foreign Office could not, at this stage, find any details of protests lodged by the British government with the US over the treatment of detainees.