Al Qaeda sympathisers have been trying to infiltrate British security service MI5, a news report said this evening.
The infiltrates tried to take advantage of a sharp expansion in MI5's numbers by applying for jobs at the agency, BBC radio and television reported.
However, the attempt failed because the suspicious applicants were weeded out during a six-to-eight month vetting process, it said, quoting government officials.
Britain's interior ministry, which speaks for MI5, declined to confirm or deny the report.
"All applicants for jobs at the Security Service/MI5 are subject to a rigorous vetting procedure and a number of candidates are turned down on security vetting grounds," it said.
The number of MI5 officers is set to rise to 3,500 from 2,600 now to try to prevent attacks such as those carried out by British Muslim suicide bombers on London transport a year ago that killed 52 people.
Once highly secretive, MI5 now advertises openly for recruits on its Web site and says it is very keen to talk to speakers of Arabic, Bengali, Urdu, Somali and Sorani (a Kurdish dialect).
Tens of thousands of people apply to join MI5 each year, with 400 making it through to final selection, the BBC said. Applicants' backgrounds and sympathies are intensively investigated.
Created in 1909 as a counter-espionage bureau, MI5 is best known for dealing with Soviet espionage during the Cold War and with Irish militant groups. But after the September 11th attacks in the United States, the British government has sought to shift MI5's priority to countering Islamic militants.