Britain's Royal Navy has opened a probe into the deaths of two sailors killed in an explosion aboard a nuclear submarine submerged under the ice cap in the Arctic Sea.

The accident, which also injured a third crewman, occurred Wednesday aboard the HMS Tireless, a hunter-killer submarine that does not carry nuclear weapons. The vessel was taking part in joint maneuvers with the U.S. Navy when the blast occurred.

British authorities say the blast had no affect on the 23-year-old submarine's nuclear power plant and say the vessel surfaced immediately afterwards.

In Washington, the U.S. Navy said a self-contained oxygen generation candle - part of the sub's air purification system - exploded.

The injured sailor was airlifted to a U.S. military hospital in Alaska, where authorities said he was expected to make a full recovery.

The British and U.S. navies have been conducting joint exercises in the Arctic since 1986.

Some information for this report was provided by AFP and AP.