Russian researchers made the first-ever dive below the North Pole in two mini-submarines last Thursday, taking rock samples from the seabed to gather proof that Russia's continental shelf stretches out into the Arctic across the Pole.
Meeting with members of the expedition - veteran explorer Artur Chilingarov and Anatoly Sagalevich, a researcher who piloted one of the submersibles - Putin said: "This has yet to be discussed with our partners, or defended in international organizations. The results of your expedition must be central to Russia's case on the issue."
In 2001, Russia said it was entitled to an extra 1.2 million square kilometers (460,000 square miles) of the Arctic, claiming the underwater Lomonosov Ridge is a continuation of its shelf. The UN demanded more evidence.
As well as collecting geological samples, the explorers planted a titanium Russian flag on the seabed, 4,200 meters (14,000 feet) below the surface, in a symbolic gesture to claim the territory believed to contain natural gas, oil, tin, gold and other riches, likely to become accessible in future decades due to man-made global warming.
Although the gesture has no legal force, it irritated Canada, which has claimed part of the Arctic shelf since 1925. A Canadian diplomat mockingly said Russia was setting up shelf borders using 15th century flag-planting methods, an allegation echoed by the United States. The countries, along with Denmark and Norway, have a 322-km (200-mile) economic zone in the Arctic under the UN Convention on the Law of the Sea.
Russia's claims prompted George W. Bush's administration to step up pressure on Congress to sign the UN Convention to be able to have its say on the body.