London - A report by the British intelligence services has claimed that "some thousands" of militant Islamists are active in the country, the Sunday Telegraph has said.

The document, which the paper describes as being drawn up by the intelligence service of the Ministry of Defence, the internal security organization MI5 and the police's Special Branch, identified the cities of London, Birmingham and Luton as particular centres of Islamist activity.

The country was a "high-priority target for international terrorists aligned with al-Qaeda."

The report said that Britain faces a threat from British nationals, including Muslim converts, British-based foreign militants, and terrorists planning attacks from abroad.

The intelligence services called the threat "diverse and widely distributed," although it could not give precise numbers of militants involved.

"Some thousands of extremists in the UK (are) committed to supporting jihadi activities, either in the UK or abroad," it said.

Last year MI5 said that there were 2,000 individuals in the country who posed a threat to national security.

MI5 has recently doubled its staff levels and opened nine regional offices in an attempt to deal with the perceived terrorism threats, the paper said.