MOSCOW (AFP) -- A Russian exploration team led by two members of parliament was carrying out tests on Sunday before an epic descent to the North Pole seabed, amid heightened international rivalry in the region.

The Arctic 2007 expedition led by veteran explorer and parliament member Artur Chilingarov is aimed at advancing Russia's claims to a swathe of Arctic seabed thought to be rich in oil and gas. The voyage reflects growing international interest in the Arctic partly due to climate change, which is causing greater melting of the ice and in turn making the area more accessible for research and economic ventures. Adding to the sense of rivalry, Russian media have reported that an American spy plane was spotted observing the expedition, although this was played down by a senior expedition official. The expedition on Sunday tested two mini-submarines near the Franz Josef Archipelago, which lies about two thirds of the way from the mainland to the North Pole, the deputy director of the Arctic and Antarctic Research Institute, Arkady Soshnikov, told AFP. The ITAR-TASS news agency reported that the mini-subs had descended to a depth of 1,300 meters (4,300 feet). After returning to the surface the explorers were to sail to the pole itself on their research vessel, the Akademik Fyodorov, which is being escorted by a nuclear-powered ice-breaker. Once there the mini-subs, with Chilingarov and fellow parliament member Vladimir Gruzdev on board, are to descend about 4,200 meters (14,000 feet) to the seabed, where they will carry out tests and leave a Russian flag. The descent was due to take place on Sunday or Monday but delays meant this could be pushed back until Tuesday, said Soshnikov. The voyage comes as several northern countries try to extend their rights over sub-sea resources beyond their economic zones, on the basis that some sections of seabed could be defined as part of their respective landmasses. Both Norway and Denmark are carrying out surveys to this end, with Denmark's efforts focused on the coast of Greenland, a Danish province, said Claes Ragner, an expert at Norway's Fridtjof Nansen Institute. ""It's kind of a race between Arctic countries to extend their continental shelves as far north as possible, to claim as much as possible of the Arctic sea bottom,"" Ragner told AFP. Russia claims a special role in the Arctic and points to a rich history of exploration there dating at least as far back as the 19th century. The Russian expedition hopes to establish that a section of sub-sea territory that passes across the North Pole, known as the Lomonosov Ridge, is in fact an extension of Russia. In 2001 Russia made a submission to a United Nations commission claiming sub-sea rights stretching to the pole. President Vladimir Putin urged greater efforts to secure Russia's interests in the Arctic in a speech aboard a nuclear-powered ice-breaker in May. After the descent to the polar seabed the Akademik Fyodorov is to go on to establish a ""drifting ice station"" on a suitable piece of ice, which will be home to 11 researchers studying climate issues, Soshnikov said. On Saturday the official Russian daily Rossiskaya Gazeta reported the alleged monitoring of Russia's expedition by a U.S. spy plane and claimed that the voyage had ""fallen under the American microscope."" This was played down by Soshnikov, who said: ""This is not the only expedition in the Arctic ... The presence of an American plane doesn't mean it came specially to see what the Russian ship was doing. We have no doubt that it was doing purely scientific research.