The month-long Danish expedition will study the Lomonosov Ridge. Russia believes the underwater feature is linked to its territory.

Denmark will investigate the ridge to see if it is geologically connected to Greenland, a Danish territory.

Canada, Norway and the US also have claims to the Arctic.

The area is believed to be rich in oil and gas reserves, which global warming could make easier to extract as the ice melts.

The Danish mission, called Lomrog (Lomonosov Ridge Off Greenland), is supported by a Swedish icebreaker called Oden and a Russian nuclear icebreaker called 50 let Pobedy ("50 Years of Victory").

The team plans to collect bathymetric, gravity and seismic data to map the seabed under the ice, according to a Danish science and technology ministry statement on the expedition.

It is due to sail from Tromsoe in northern Norway, returning to Norway's remote Svalbard islands on 17 September.

Canada said yesterday it will build two military facilities in the far north in a bid to assert its sovereignty over the contested Arctic region.

Prime Minister Stephen Harper made the announcement during a tour of Canada's northern territories.

Last week, a Russian expedition planted the country's flag on the floor of the Arctic Ocean 14,000 ft under the North Pole.

Harper said a coldweather army training base would be set up at Resolute Bay and an existing port at a former mine at Nanisivik would be refurbished to supply Arctic patrol vessels.

The North Pole seabed is not currently regarded as part of any single country's territory.