WASHINGTON (AFP) - US and Canadian air defenses were placed on heightened alert after a shooting in Canada's parliament, US officials said Wednesday.

The North American Aerospace Defense Command (NORAD) "is taking appropriate and prudent steps to ensure we are adequately postured to respond quickly to any incidents involving aviation in Canada," said a US defense official, who spoke on condition of anonymity.

The move came as a precaution after a gunman opened fire in and around the Canadian parliament, with a Canadian soldier dying of gunshot wounds and police sealing off the area.

NORAD spokesman Captain Jeff Davis declined to provide details of the steps taken, saying only steps had been taken to ensure defenses were "adequately postured."

But while the shooting incident in Ottawa raised fears of a potential link to extremists, Davis said there were no signs of possible hijackings or imminent threats to aviation.

"We're not aware of any current, specific threats against the aviation system," he told AFP.

US intelligence officials were not immediately available to comment as to whether there were any suspected links to extremists in the shooting in Canada.

NORAD, founded during the Cold War, is a combined US, Canadian military command designed to safeguard the air space over the two countries, with its headquarters at Peterson Air Force Base in Colorado.

After the attacks on New York and Washington on September 11, 2001, the command regularly scrambles fighter jets to intercept private aircraft that enter prohibited areas over the US capital or elsewhere, escorting them to the nearest runway.