“Networks linked to AQ Core pose the greatest threat to the UK," stated the report by the Joint Terrorism Analysis Center at Britain’s MI-5 headquarters and obtained by the Daily Telegraph.

The report said there is a potential threat from Al Qaida in Iraq. “A member of this network is reportedly involved in an operation which he believes requires AQ Core authorization,” the report said.

“We assess that this operation is most likely to be a large-scale, mass casualty attack against the West," stated the report, noting that Al Qaida networks are active in Britain.