The US and Canadian governments have released details of a planned 42-day Arctic Ocean mapping mission as part of the two countries' efforts to extend their sovereignty over resource-rich areas of the polar seabed.

The scheduled survey of a subsea mountain range in waters far to the north of the Alaska-Yukon border, to be carried out jointly with scientists from the US and Canada, follows a similar collaborative research expedition last summer in the Beaufort Sea.

As they did last year, the US Coast Guard cutter Healy and the Canadian Coast Guard icebreaker Louis S St-Laurent will rendezvous in the ocean west of the Canadian Arctic archipelago to begin carrying out the survey on 6 August, according to a Canwest News Service report.

Last summer's mapping mission was considered a major success, partly because an unprecedented retreat of sea ice from the Beaufort left scientists a clear path to quickly and thoroughly survey a wide swath of the ocean.

Officials said at the time that the sharing of specialised surveying equipment and other resources also allowed each country to map a much greater area of the sea floor than if they'd been working independently.

All five nations with an Arctic Ocean coastline — Canada, the US, Denmark (Greenland), Norway and Russia — are working under provisions of a United Nations treaty to gain control of subsea territory.

The challenge is to identify — through sonar surveys of the ocean floor and other geological evidence — areas of the seabed that are linked to each country's continental shelf.

Norway has already been granted sovereignty over several large tracts of Arctic and North Atlantic seabed under the UN Convention on the Law of the Sea.

The Norwegian government has also announced it will make no claim to areas in the deeper Arctic Ocean near the North Pole, conceding that Canada, Russia and Denmark have stronger cases for asserting sovereignty along the potentially oil-rich Lomonosov, Alpha and Mendeleev subsea mountain ridges.