The deputy director of the Canadian Security Intelligence Service, Jack Hooper, told a Senate committee studying Canada's role in Afghanistan that there are people living in Canada who fought with al-Qaida during the Soviet occupation of Afghanistan.

The Senate Standing Committee on National Security and Defense held a full day of hearings on Canada's military mission in Afghanistan, and how it relates to security at home.

The hearings come as Canadians and some lawmakers voice growing concern over the deaths of Canadian soldiers serving in Afghanistan as part of a NATO force. Parliament voted earlier this month to extend Canada's mission in Afghanistan until 2009.

Canada has about 2,000 soldiers based in Afghanistan, most of them in Kandahar.

In outlining the domestic threat, he pointed to examples of people who had lived in Canada who later took part in terrorist attacks. A common thread among them was time spent at training camps in Afghanistan.

"When we talk about the homegrown terrorist phenomenon, these are people ... in most instances who are Canadian citizens," he said. "A lot of them were born here. A lot of them who were not born here emigrated to Canada with their parents at a very young age."

Hooper did not provide any specifics on numbers of potential terrorists or their whereabouts. It also wasn't clear what the agency was doing in relation to monitoring or possibly questioning and detaining potential terrorists. Canadian Press news agency said Hooper did not respond to questions from reporters after the hearing.

"I can tell you that all of the circumstances that led to the London transit bombings ... are resident here and now in Canada," said Hooper, the service's operations director, referring to the bombings in Britain's capital that killed 52 civilians and four terrorists last July 7.

Committee chairman Sen. Colin Kenny said the attacks on Britain should serve as a wake-up call for the problems Canada could encounter with homegrown terrorists.

"They'd been born in country," Kenny said of the London bombers. "They had all of the slang and comfort with the culture that you and I have, and yet, boom, here they are committing terrorist acts."