The rust-proof titanium flag was planted on the seabed 4,261 meters (13,980 ft) under the surface of the Arctic Ocean, Itar-Tass news agency quoted Vladimir Strugatsky, vice president of Russia's polar exploration association, as saying from a support vessel.
Russia wants to extend the territory in the Arctic it controls right up to the North Pole. The region is believed to hold vast untapped oil and gas reserves.
Under international law, the five states with territory inside the Arctic Circle -- Canada, Norway, Russia, the United States and Denmark via its control of Greenland -- have a 320 km (200 mile) economic zone around the north of their coastline.