Moscow — President Medvedev said yesterday that Russia should unilaterally claim part of the Arctic, stepping up the race for the disputed energy-rich region.

“We must finalize and adopt a federal law on the southern border of Russia’s Arctic zone,” Mr. Medvedev said. “This is our responsibility, and simply our direct duty, to our descendants.

“We must surely, and for the long-term future, secure Russia’s interests in the Arctic.”

Global warming has stepped up the fight for the disputed Arctic, believed to be laden with vast reserves of oil and gas. Russia has pitted itself against Canada, Denmark, Norway, and America to fight for a greater part of the region, arguing that most of it is Russian territory since an underwater ridge links Siberia to the North Pole’s seabed.

Last August, a Russian mini-submarine carrying politicians and scientists dived to the depths of the Arctic and claimed to plant a Russian flag to mark Moscow’s stake in the territory.

Footage of the alleged planting was widely broadcast on Russian television, but turned out to be images taken from the Hollywood film Titanic.

Under international law, each of the five countries that lay claim to the Arctic own a 200 mile zone that extends north from their shores. That arrangement is up for U.N. review next May.