By Deborah Zabarenko, Environment Correspondent

WASHINGTON, Aug 9 (Reuters) - Russia's symbolic claim to Arctic mineral wealth must be decided by a U.N. commission, and then only if experts determine the area is an extension of the Siberian continental shelf, Russian experts said on Thursday.

One week after Russian explorers used a submersible vehicle to place their country's flag on the seabed beneath the North Pole, the head of Russia's Institute of Oceanic Studies called the event "heroic" but said the claim would be settled "strictly within the framework of international law."

The matter would come before the U.N. Commission on the Limits of the Continental Shelf, but not until scientists drill deep for seabed samples to find out if the continental shelf extends to the area under the pole, said Robert Nigmatulin, who also chairs the Russian State Duma Council on Ecology.

"These rock formations are going to be the only solid proof of Russia's claim," Nigmatulin said in a videoconference from Moscow. "Only after that will it be appropriate to raise the legal issues about the claims of neighboring states to that ground."

This kind of deep drilling is not technologically possible now, said Nikolai Osokin of the Geographical Institute of the Russian Academy of Sciences.

There is a planned German icebreaker vessel, the Aurora Borealis, that might be able to do the job, but it is not expected to be operating before 2013. Russia has offered expertise to the project but no money.

Harley Balzer of Georgetown University, participating in the videoconference from Washington, applauded Russian President Vladimir Putin's measured response to the flag-laying, but questioned those in the Russian Duma who have been "a little less careful" in praising the stunt.

UNDERWATER MOUNTAIN

Canada, Denmark, Norway, Russia and the United States all have territory within the Arctic Circle, and have a 200-mile (320 km) economic zone around the north of their coastlines.

Norway neither contests nor supports Russia's claim, and is seeking an extension to its subsea territory in the Arctic, but not as far as the North Pole.

Norwegian oil companies are also pushing north in the Barents Sea, such as Statoil's <STL.OL> Snoehvit gas field off the northern tip of Norway due to start up in October. Better technology and global warming may make the icy region more accessible in the future.

The Danish foreign ministry said the flag-laying had no legal significance, and that Denmark reserves the right to make its own continental shelf claim to the United Nations on behalf of Greenland.

Russian geologists estimate the Arctic seabed has at least 9 billion to 10 billion tonnes of fuel equivalent, about the same as Russia's total oil reserves.

These geologists base the Russian Arctic claim on a belief the Lomonosov ridge, a vast underwater mountain range that runs underneath the Arctic, is an extension of Russia.

Russian explorers are planning another Arctic expedition this year.

(Additional reporting by Alister Doyle in Oslo, Gelu Sulugiuc in Copenhagen)

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