The Tablighi Jamaat, a conservative Islamic missionary group founded in India 75 years ago, has come under the scrutiny of US investigators, a media report said on Monday.

"We have a significant presence of Tablighi Jamaat in the United States, and we have found that Al Qaeda used them for recruiting, now and in the past," Michael J Heimbach, the deputy chief of the Federal Bureau of Investigation's international terrorism section, was quoted as saying by the New York Times.

The Tablighi Jamaat, which describes itself as a non-political, non-violent group interested only in 'proselytising and bringing wayward Muslims back to Islam', attracted US investigators' interest following the September 11, 2001, attacks.

Another senior law enforcement official described the group as 'a natural entree, a way of gathering people together with a common interest in Islam'.

"Then extremists use that as an assessment tool to evaluate individuals with particular zealousness and interest in going beyond what's offered," he said.

According to officials, the group has been 'caught up' in terrorist cases because of its global reach and reputation for rejecting such worldly activities as politics, precisely the qualities that are exploited by terror groups like Al Qaeda.

The leaders of the Tablighi Jamaat said the scrutiny is 'unwanted and grossly unfair' as their beliefs are against everything espoused by Osama bin Laden and the Al Qaeda.

"It is a very great accusation, a total lie," said Abdul Rahman Khan, a leader of the group's North American council.

Khan, involved with the group for 36 years, said the Tablighi Jamaat's refusal to discuss politics means that people with 'militant views' quickly move on. "If someone starts even one word, we cut him off. So he's going to go somewhere where he can get an audience.

"We don't prevent anyone from coming, but obviously we don't know the nature of the individual who is coming and we don't check. There's no way we can."

Neither the group nor its activists have been accused of committing any crime or of supporting terrorism. Still, the authorities remain alert to what they see as the organisation's 'susceptibility to infiltration and manipulation', the report said.

Tablighi Jamaat in Arabic means a 'group that propagates the Faith', and its members visit mosques and college campuses in small bands, preaching a return to purist Islamic values.

According to the report, the Tablighi Jamaat, is less a formal organisation than a network of part-time preachers. It now has bases and schools in Pakistan, Britain and Canada and its annual gatherings in India and Pakistan draw thousands of people.