NEW YORK, Oct 6: The Federal Bureau of Investigation has begun investigations into the lives of thousands of young Muslims living in the United States who they believe have Al Qaeda connections.

A report in the Sunday edition of the New York Times, said that senior law enforcement officials say the surveillance campaign is being carried out by every major FBI office in the country and involves 24-hour monitoring of the suspects’ telephone calls, e-mail messages and Internet use, as well as scrutiny of their credit-card charges, their travel and their visits to neighbourhood gathering places, including mosques.

American counterterrorism officials have estimated that 10,000 to 20,000 young Muslims from around the world trained in Osama bin Laden’s camps in Afghanistan.

Since the Sept 11 attacks, with information gathered from abandoned Qaeda hideouts in Afghanistan and Pakistan and from captured terrorists, the officials have tried to compile the names of everyone who attended the camps. So far, the officials say, they have been able to identify and track down several hundred people around the world who trained at the camps and might be considered a threat the Times said.

The FBI campaign, which has also involved efforts to recruit the suspects’ friends and family members as government informers, has raised alarm from civil liberties groups and some Arab-American and Muslim leaders.

The Times said that the US law enforcement officials say the surveillance programme has provided vital evidence to support a string of arrests and indictments around the country since late summer — in western New York, in Detroit, in Seattle and, on Friday, in Portland, Ore. — of Americans and others accused of conspiring in terrorist cells to assist Al Qaeda.

However, the paper pointed out that the FBI has acknowledged that it has no evidence of any imminent terrorist threat posed by the so-called sleeper cells connected to Al Qaeda. Federal law enforcement officials say there is no sign of a terrorist cell operating on American soil that, in its level of commitment and training, resembles anything like the team of suicide hijackers who trained in the United States for several months before carrying out the Sept 11 attacks.

They concede that the domestic threat posed by Qaeda cells may at times have been overstated, especially after the arrest last May of Jose Padilla, an American also known as Abdullah al-Muhajir. Justice Department officials have backed away from their initial suggestion that they had compelling evidence linking him to a plot to build an explosive radiological device known as a dirty bomb the paper said.

Nevertheless law enforcement officials told the paper that they are convinced that at least several dozen people now under FBI surveillance in the United States — with different degrees of terrorist training, and with varying degrees of loyalty to Al Qaeda — would take part in an attack if ordered, and that they represent a clear threat.

“If you look at the number of people who went through the Al Qaeda training camps, and there are literally thousands who did, it stands to reason that a certain percentage of them are in this country,” John E. Bell, Jr., who retired last summer as the special agent in charge of the FBI’s field office in Detroit told the paper. Much of the surveillance campaign is centered in Detroit, since the region is the home to the nation’s largest population of people of Arab descent.

The NYT points out that Arab-American and Muslim groups have complained that the intense FBI surveillance campaign, which they insist has been evident for months, has unfairly left the perception that all young men of Arab descent or the Muslim faith have some connection to terrorism.

“Young Arab men, in particular, are being treated as suspicious, possibly dangerous,” said Hussein Ibish, communications director of the American-Arab Anti-Discrimination Committee. “I think there have been some really egregious instances of abuse.”

But he told the paper there was an understanding among Arab-Americans that a handful of young men of Arab descent in the United States might pose a terrorist threat, and that it was in the best interests of the community here to find and stop them. “I would be surprised if there are hundreds of them,” he said. “But there could be 10, 20, 30.”