In a seven-page statement to the law lords, Eliza Manningham-Buller said experience showed that material received from foreign authorities as a result of what she called "detainee reporting" had "proved to be very valuable in disrupting terrorist activity".

Ms Manningham-Buller said that MI5 and the secret intelligence service MI6 did not, as a rule, inquire closely into the origin of information received from foreign security agencies, especially when an urgent response was needed. "Where circumstances permit", the agencies would seek to acquire "as much context as possible" about how the information was obtained, she wrote. But she added: "Where the reporting is threat-related, the desire for context will usually be subservient to the need to take action to establish the facts, in order to protect life." The Law Lords are considering an earlier Appeal Court ruling that evidence obtained by abuse of detainees overseas may be admissible in a British court, so long as UK agents do not participate in or solicit it.

Ms Manningham-Buller's comments, seen by Channel 4 News, are contained in a statement to law lords hearing an appeal by 10 terror suspects who argue that evidence from torture overseas should not be used in the Home Office's attempt to deport them.

A Home Office spokesman said it would not comment on the case.