The Mir-1 submersible reached the seabed at 12:08pm Moscow time (08:08 GMT), one of two crafts taking part in the exploration.
Mir-1 successfully returned to the surface on Thursday via a large entry hole cut into the icecap, after a tense 40-minute ascent.
The second vessel, whose crew included a Swede and an Australian, emerged to the surface about one hour later.
"It was so good down there," said Chilingarov after the flag had been anchored.
"If someone else goes down there in 100 or 1,000 years, he will see our Russian flag."
Under international law, five states have territory inside the Arctic Circle - Canada, Norway, Russia, the United States and Denmark, via its control of Greenland.
Moscow's attempt to claim a larger area of the Arctic Circle extending as far as the pole is based on its contention that the Arctic seabed and Siberia are linked by one continental shelf.
"Then Russia can give foundation to its claim to more than a million square kilometres of the oceanic shelf," said a newsreader for Russia's state news channel Vesti-24 during the expedition.
Oceanographers also studied the seabed in an effort to establish that Russia and the North Pole are part of the same shelf.
Sergei Lavrov, foreign minister, said: "The aim of this expedition is not to stake Russia's claim, but to show that our shelf reaches to the North Pole."
Tom Casey, a US state department spokesman, said Russia was entitled to submit its claim "as members of the Law of the Sea convention."
|A Russian state flag was fixed |
to the seabed [AFP]
However, he dismissed the significance of planting a flag in the North Pole seabed.
"I'm not sure whether they put a metal flag, a rubber flag or a bedsheet on the ocean floor," he said. "Either way, it doesn't have any legal standing."
Peter Mackay, Canada's minister of foreign affairs, also dismissed Russia's move.
"Look, this isn't the 15th century... You can't go around the world and just plant flags and say 'We're claiming this territory'."
Soviet and US nuclear submarines have often travelled under the polar icecap, but no craft has so far reached the seabed under the pole.
The Arctic seabed is thought to contain resources of natural gas, said Chris Weafer, chief strategist at Alfa Bank in Moscow.
"The exploration that has taken place in the Arctic over the past 15 years, made possible because of the receding icecap, has given very positive indications of substantial structures, particularly natural gas structures," Weafer said.