Days after Russia planted a flag on the sea-bed at the North Pole, Canada responded by sending Stephen Harper, the prime minister, on a three-day trek to the region.

“Our government has an aggressive Arctic agenda,” Dimitri Soudas, Mr Harper’s spokesman, said. “The Russians sent a submarine to drop a small flag at the bottom of the ocean. We’re sending our prime minister to reassert Canadian sovereignty.”

The Northwest Passage, which is the main focus of the dispute, has become a sought-after territory thanks to global warming, which has begun to melt the ice in these waters, exposing a potentially vast haul of natural resources.

Studies have estimated that the Arctic has as much as 25 per cent of the world’s undiscovered oil and gas.

Since the Russian expedition was discovered last month, Mr Harper has faced increasing pressure to fight back.

“Canada has a choice when it comes to defending our sovereignty over the Arctic,” said Mr Harper as he announced plans last month to spend about C$3.1bn (€2.14bn) on the construction of up to eight patrol vessels capable of breaking through much of the Arctic ice. “We either use it or lose it. And make no mistake – this government intends to use it.”