The critical step to search the missing Malaysia Airlines flight MH370 at this moment is to confirm the place of debris, Australian search operation commander Peter Leavy said on Sunday.

After the confirmation, the U.S. towed pinger locator and an underwater drone can hunt for the black box, he said.

"Our primary focus at the moment is to use the aircraft to identify the wreckage. Ships move in to pick up the wreckage from the water, then confirm or deny whether they are from the missing aircraft or not," Leavy told reporters here.

"We will use the information to track the most likely impact point of the missing aircraft, and can then deploy the appropriate equipments and detect that black box," he said.

According to the commodore, the Australian navy support ship Ocean Shield will be equipped with the U.S. device and set out to search for the black box of MH370.

When asked about the difficulties to track the black box, Leavy admitted it is an unprecedented situation which is "very challenging," adding the multinational forces are very committed to putting as much efforts as they can to locate the black box as soon as possible.

Answering the question from Xinhua about the battery life of the black box, Captain Mark Matthews, the U.S. navy supervisor of salvage and diving, said the battery would last around 45 days instead of 30 days.

"Usually we say it lasts 30 days, but it would last longer than that. I would say around 45 days," said Matthews.

A Xinhua reporter at the navy base saw equipments and supplies being loaded to the ship and the U.S. underwater drone waiting for the final examination at the wharf.