The threat of homegrown terrorists attacking Britain is greater now than any time since the Sept. 11 attacks in the United States, a British Sunday newspaper reported, citing a leaked intelligence document.

More than 2,000 British-based Islamic terrorists are believed to be plotting attacks, according to a government threat assessment prepared this month, which The Sunday Telegraph said it had seen.

"The scale of Al Qaeda's ambitions towards attacking the U.K. and the number of U.K. extremists prepared to participate in attacks are even greater than we previously judged," the newspaper quoted the document as saying.

The newspaper said the document was being circulated between the Home Office, defense ministry, M15 intelligence agency and Scotland Yard's Anti-Terrorist Branch.

Click here to read the original article on the Telegraph Web site.

The Home Office declined to comment on the report, but said in a statement that security arrangements are under constant review.

"As (MI5 Director-General) Eliza Manningham-Buller has stated publicly, the threat of terrorism in the U.K. is very real and includes the intent to kill people and damage our economy," the statement said.

Manningham-Buller said in November that 1,600 people were suspected of involvement in terrorist plots against British targets.

Four suicide bombers killed 52 commuters in July 2005 transit attacks in London and security officials say they have foiled at least six other plots. Officials expect the number of plots to increase this year, newspaper said.

The report also said Afghanistan is expected to increasingly become a magnet for Islamic extremists seeking to fight Western military forces.

NATO is struggling to persuade its members to send more troops to southern Afghanistan where the alliance is fighting a growing Taliban insurgency that left 4,000 dead last year.

"With violence in Afghanistan intensifying, and therefore receiving greater media attention, the country may well become more attractive as a venue for foreigners wishing to fulfill their Jihad ambitions," the newspaper quoted the report as saying.

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