Russia said today it was ready to evacuate soldiers and civilians from the Pacific Kuril archipelago and Sakhalin island if the nuclear danger from a quake-damaged Japanese atomic plant worsened.

The Kuril islands lie just north of Japan's northern Hokkaido island and the southernmost four islands in the chain are still claimed by Tokyo, in a dispute that has prevented the signing of the World War II peace treaty.

Sakhalin meanwhile is a much larger island with a population of half a million which lies just off Russia's Far Eastern coast and serves as a crucial hub for the oil and gas industry.

"The officers in the region are watching the situation at the Japanese nuclear power station," a spokesman for the military's Far Eastern district told the RIA Novosti news agency.

"We are ready to carry out a timely evacuation of the military service people, their families and the civilian population from the Kuril islands and Sakhalin, if the need arises," the spokesman added.

The spokesman said any evacuation would be carried out by vessels from Russia's Pacific Fleet as well as military aircraft. Evacuees could then be housed in military accommodation in the Vladivostok and Khabarovsk regions on the mainland.

Russian officials have yet to sound alarm over the radiation dangers from the Fukushima plant despite the proximity of Russia's Far East, saying that available data has yet to show any major risk.

Meanwhile, the Kremlin has said it is ready to boost energy supplies to Japan to make up the shortfall created by the 8.9 magnitude earthquake, in a move some observers say could warm relations between the two sides.