OTTAWA — Canada will not tolerate Russian intrusions into Canadian airspace, Prime Minister Stephen Harper said Friday after it was disclosed that two Russian bombers were intercepted just outside the Canadian Arctic shortly before U.S. President Barack Obama's visit to Ottawa this month.

"I have expressed at various times the deep concern our government has with increasingly aggressive Russian actions around the globe and Russian intrusions into our airspace," the prime minister said at a news conference in Saskatoon.

"This government has responded every time the Russians have done that. We will continue to respond; we will defend our airspace."

Earlier Friday, Defence Minister Peter MacKay disclosed that two CF-18 fighter jets met at least one Russian bomber within 24 hours of the U.S. president's trip to Ottawa on Feb. 19 just outside of Canada's Arctic airspace.

The incident set off a round of bitter sniping between Moscow and Ottawa that was a throwback to the Cold War era.

Initially there was confusion over the number of Russian planes involved — it turned out to be two, not one — while Russian sources mocked Canada's assertion that they were given no notice of the flights.

With Obama poised to leave U.S. soil for the first time as president on Feb. 19, the joint Canada-U.S. aerospace command, Norad, picked up the approaching aircraft.

Canadian jets were scrambled and sent "very clear signals" to the Russian aircraft to "turn tail and head back to its own airspace," which were followed without incident, MacKay said.

Later Friday, Canadian defence and Norad officials confirmed a second Russian plane was involved in the incident, and identified the two aircraft as Tupolev Tu-95 propeller driven bombers, a type of aircraft known as the "Bear."

Vladimir Drik, an aide to the Russian chief of staff, speaking to RIA Novosti news agency confirmed the Feb. 18 flight, but indicated a different model of Tupolev carried out the mission.

"The Tupolev-160 fulfilled all its air patrol tasks. It was a planned flight."

He said the crew acted solely within the limits of international air agreements and did not violate Canadian airspace.

At the time, Canada was preparing to host the rookie president on his first international trip after weeks of preparation that included tight security.

Indeed, the airspace over Canada's capital was temporarily closed to all planes but Obama's own Air Force One, which arrived and then departed after the seven-hour visit.

"It's not a game," said MacKay.

"I've personally asked both the Russian ambassador and my counterpart that we are given a heads-up when this type of air traffic is to occur. And to date we have not received that kind of notice that would be preferable."

The Russian Embassy in Ottawa had no comment Friday.

MacKay said Obama's impending arrival in Ottawa was well known to everyone.

A Russian military source reportedly scoffed at Canada's claims.

"So the statements from Canada's defence ministry are perplexing to say the least and cannot be called anything other than a farce," Russia's Interfax news agency quoted an unnamed source as saying, according to Reuters.

In Ottawa, MacKay raised questions about the timing of Russian flight.

"I'm not going to stand here and accuse the Russians of having deliberately done this during the presidential visit, but it was a strong coincidence, which we met with a presence, as we always do, of F-18 fighter planes."

In Saskatoon, Harper said Canada would continue to fulfil its obligations to defend North America's continental airspace.

"We will respond every time the Russians make any kind of intrusion on the sovereignty of Canada's Arctic," he said. "That's our obligation and that's what we'll do."

The incident was disclosed Friday morning at a joint news conference on Parliament Hill with MacKay, Gen. Walt Natynczyk, the chief of the defence staff, and U.S. Gen. Gene Renuart, the commander of Norad.

Natynczyk said the incursions started about one and a half to two years ago "when we had not seen anything for decades."

He declined to say how often they occur or where exactly this particular incident took place.

"It's sporadic. That's the best way I can describe it," he said.

He lauded the professionalism of the Canadian pilots. "The last incursion again was textbook," he said. "We have very professional people."

Renuart said pilots typically rely on internationally recognized visual signals and international flight guidelines.

"We do broadcast on a common frequency that you're approaching Canadian or U.S. airspace and you must turn to avoid entering that airspace. But there are also visual signals, from as simple as wagging wings to making turns to kind of lead that aircraft off in another direction," Renuart said.

"While we do not speak the common language, they are trained in those common signals just as we are, and to date those have been effective in deviating or deterring those aircraft from entering into either Canadian or U.S. airspace."

In 2007, Russia planted its flag on the seabed below the North Pole and resumed flights of strategic bomber jets over the Arctic Ocean, a practice that stopped after the fall of the Soviet Union.

The Harper Conservatives have since unveiled an Arctic strategy to assert Canadian sovereignty, and spur economic and social development in the Far North.

Relations between Russia and the West have been strained since last August when Russian forces marched into Georgia following the Georgian army's occupation of the breakaway province of South Ossetia.

Weeks after that, MacKay travelled to Iqaluit to reinforce his Conservative government's new Arctic sovereignty policy, where he put Russia on notice that Canada intended to be vigilant about foreign incursions in the region.

Norad is the jewel of Canada-U.S. military relations, and it celebrated its first half-century last year.

Norad was conceived in the Cold War to serve as an early-warning system against a nuclear missile attack from the then Soviet Union.

Since the fall of the Berlin Wall, and following the Sept. 11, 2001, terrorist attacks, it remains a major tool in the defence of North America.

A Canadian officer permanently holds the No. 2 position at Norad headquarters in Colorado Springs, Colo.

On the morning of 9/11, it was a Canadian general who was on duty and who ordered the closure of North American airspace, and who dispatched Canadian and U.S. warplanes into the continent's skies moments after New York and Washington were attacked by hijacked commercial airliners.

With a file from James Wood, Saskatoon StarPhoenix, and Agence France-Presse