Italian Prime Minister Silvio Berlusconi told reporters this week that a stubborn bear had fallen foul of the security.

A Canadian security official confirmed the bear was shot by an Alberta provincial wildlife officer inside the security zone on Monday, but said she had no other details, such as what kind of bear it was. Alberta authorities were not immediately available for comment.

"The bear didn't want to leave the protected zone. They fired a tranquilizer dart at it. Unfortunately instead of hitting a muscle, because of an abrupt movement, they hit its heart and the bear died," Berlusconi said.

"Everyone was sorry and so of course were we," he added.

Bears as well as cougars and mountain sheep are regularly sighted in the Canadian Rockies and are protected by local laws.

Canada has been eager to present the two-day summit as a "green event," offering the media environmentally friendly information kits using only natural fibres, eco-certified paper and vegetable-based inks.