Manningham-Buller voices hopes for al-Qaeda peace talks
The former head of MI5 says she hopes British and US intelligence are examining ways of talking to al-Qaeda, with a view to an eventual settlement.
But Baroness Manningham-Buller, who ran the security service until 2007, said negotiations were a way off.
She was speaking in London on Thursday, as she delivered the first of her BBC Reith lectures on the theme of "Securing Freedom".
She also branded the 9/11 attacks "a crime, not an act of war".
Baroness Manningham-Buller said: "What I think is that I hope - I don't know - that thinking about the answers to those questions is something that is currently happening.
"And therefore people - I hope - in the American intelligence world and in our own, are thinking exactly... who to talk to, how to talk to them and what we might discuss."
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Eliza Manningham-Buller's Reith Lectures start on BBC Radio 4 from Tuesday 6 September 2011 at 09:00 BST
She went on to say that it would be "foolish" for the security services to say "that you're never going to speak to them or never going to try to."
The former head of MI5 said that military and security responses to terrorism can only go so far.
She added that, eventually, "you have to reach a political settlement" with terror groups.
Baroness Manningham-Buller ran the security service for five years and presided over a massive expansion in it.
She said she had always found the phrase "war on terror"' to be unhelpful and that the Iraq invasion had been a distraction in the West's pursuit of al-Qaeda.
As she delivered the first of her three BBC Reith lectures, Baroness Manningham-Buller said the Iraq invasion had provided an arena for jihad and had motivated some Britons to embark on terrorism.