Security chief says terror threat to Britain falls

LONDON, Jan 7 (Reuters) - The threat of an immediate attack in Britain by al Qaeda-inspired militants has receded after several prosecutions but networks remain active, the head of the country's national intelligence agency was quoted as saying.

British newspapers said the spy chief had commented that Israel's attack on Gaza could inspire further extremism and warned that the economic fallout from the global credit crunch may bring fresh security risks.

In the first interview to newspapers given by a serving head of Britain's MI5 domestic Security Service, Jonathan Evans noted there had been 86 convictions since January 2007 with nearly half pleading guilty.

"This has had a chilling effect on the enthusiasm of the plotters and they are keeping their heads down," he said in comments published on Wednesday.

"There have been fewer cases where terrorists have moved from facilitating and supporting terrorism to attack-planning."

Four British Muslim men carried out suicide bomb attacks on the London transport system in July 2005, killing 52 people.

Britain has been a target for Islamist militants after it joined the United States in invading Afghanistan and Iraq after the Sept. 11, 2001 attacks on the United States.

Evans said there was no cause for complacency. "There is a seedbed of networks of extremism in the UK from where attacks could come."

Britain has never fallen below its second highest threat level of "severe" since first publishing the warning status in August 2006.