Canada's foreign affairs department is investigating as-yet unconfirmed reports that a key source of recent intelligence on al Qaeda is a Canadian citizen.

Mohammad Naeem Noor Khan, 25, was arrested in Pakistan on July 13. The computer expert helped relay e-mail messages to his al Qaeda contacts.

Twelve days later, Ahmed Khalfan Ghailani was arrested in Gujrat, Pakistan. He is a major al Qaeda figure wanted in connection with 1998 attacks on U.S. embassies in Tanzania and Kenya that killed 224 people. There was a $25 million US reward for his capture.

Khan's capture led to the discovery of various stored computer data including images of possible terror targets in England such as London's Heathrow airport.

However, his effectiveness may have been hurt after U.S. officials leaked his name to the New York Times.

That paper reported Friday that American officials now believed that Khan had also played an operational role in gathering information about American targets.

Those included the Citigroup Building and New York Stock Exchange, the Prudential Building in Newark, N.J. and the International Monetary Fund and World bank in Washington, D.C.

"A fluent English speaker who traveled internationally, Mr. Khan spent time in Britain as recently as November 2002 ...," the Times said.

Khan had been largely unknown to U.S. intelligence until May, although they had been aware of him through his alias -- Abu Talha.

His father, who lives in Karachi, told the Associated Press he hadn't heard from his son in years, indicating there had been a falling-out.

Other arrests

A U.S. officials said Friday that another man arrested in Britain was a senior al Qaeda operative.

They believe that Abu Musa al-Hindi wrote surveillance reports on those five U.S. financial institutions that were identified as targets in Monday's terror alert.

The Washington Post and some British newspapers reported that al-Hindi was also suspected in planning an attack on Heathrow.

About 20 people have been detained in Pakistan in the past month, while Britain is still holding 12 people from raids conducted Tuesday. It released one person.

Another arrest in Britain was announced Thursday. Babar Ahmad, a British citizen, is wanted in the United States on terrorism-related charges.

He is accused of trying to raise funds to support terrorist activities in Chechnya and Afghanistan between 1998 and 2003.

U.S. officials say that some of the websites Ahmad used to solicit money were based in Connecticut.