Japan and Australia said on Thursday they were closely watching oil prices for any impact from hostilities in Ukraine, with Australia saying it was prepared to tap its oil stockpile held in the United States if global supplies are hit.

The Bank of Japan would closely monitor how escalating tensions in Ukraine could affect oil prices, given Japan's heavy reliance on energy imports, Governor Haruhiko Kuroda told parliament.

Australia's energy minister, Angus Taylor, said any move to tap the small stockpile that Australia holds in the United States Strategic Petroleum Reserve would be in coordination with other International Energy Agency (IEA) members.

Oil prices jumped to seven-year highs this week on worries that oil and gas supplies could be disrupted if Russia launches an all-out invasion of Ukraine at a time when global oil stockpiles are tight.

"While we cannot control these international price spikes, we are closely monitoring the situation with the IEA and the United States and stand ready to take action to help alleviate these pressures," Taylor said in a statement.

The IEA said earlier this week member countries stood ready to act together to ensure global oil markets are adequately supplied.

Total oil stocks in IEA member countries stood at close to 4.16 billion barrels as of end-December, including 1.5 billion barrels held by governments in emergency reserves, the IEA said on Feb. 22.

Australia holds 1.7 million barrels in the U.S. Strategic Petroleum Reserve.