TORONTO - Climate change is destroying the country's North as we know it and the federal government is not doing enough to protect Canada's Arctic sovereignty, NDP Leader Jack Layton said Sunday.

"The Russian mission to place its flag on the ocean floor at the North Pole demonstrates a troubling reality for Northern communities and all Canadians concerning Arctic sovereignty," Layton said in a letter sent to Prime Minister Stephen Harper, who's due to visit several Northern communities this week.

A Russian expedition reached the North Pole on Wednesday, and scientists sent two mini-submarines under the ice to mark the sea floor Thursday with a Russian flag. The voyage's chief goal appeared to be advancing Russia's political and economic influence by strengthening its legal claims to the huge gas and oil deposits thought to lie beneath the Arctic sea floor.

Layton criticized the government's decision to buy up to eight medium ice-strengthened military patrol vessels, instead of three heavy ice-breakers it promised during the last election, saying it is "misguided."

"Canada must move quickly to make immediate, strategic investments in its Arctic and recognize that the greatest challenges in the North are social, economic and environmental," said Layton.

Foreign Affairs Minister Peter MacKay said the NDP is "just plain wrong" when it claims that Canada is not exercising its legitimate rights in the Arctic.

The Russian mission to the North Pole has done nothing to affect Canada's claims over the Arctic, MacKay said in a statement.

"Canada's sovereignty over our arctic region is rooted in an historic connection to the land, its continued habitation by the Inuit people and our constant assertion of our sovereign claims."

The government believes the Canadian Forces must have the capability to operate more effectively in the Arctic, the minister said.

Layton's statements about the new patrol ships are misleading, Mackay said, and the vessels "will provide the flexibility for the Navy to operate in both the Arctic and offshore environments, allowing them to be used year-round in a variety of roles, including domestic surveillance, search and rescue, and support to other government departments."

Critics claim Canada has done little to assert its sovereignty in the Arctic since 2003, when this country signed an international treaty that set the clock running for countries to stake out their territory in the polar sea.

Under international law, five Arctic countries - Canada, Russia, the United States, Norway and Denmark - control an economic zone within 320 kilometres of their continental shelf. But the definition of the limits of that shelf are in dispute.

Ottawa has long maintained that Canada's sovereignty over the lands and waters of the Canadian Arctic is longstanding, well-established and based on historic title.

Harper has called the Arctic "central to our identity as a northern nation."