Tim Farrar, a satellite communications consultant in Menlo Park, California, one of a group of satellite experts who have been conducting their own independent analysis of clues to the final resting place of Flight 370, expressed surprise that the search area had not been moved even farther south-west. The plane disappeared March 8 with 239 people aboard during a flight from Kuala Lumpur, Malaysia, to Beijing.

The new location is consistent with the plane having travelled south at a speed of about 380 knots after it disappeared from Malaysian radar while over the northern end of the Strait of Malacca, Farrar said. The area of the sea floor that was checked in April and May, after US Navy contractors thought they had heard acoustic pings from the aircraft's "black boxes," was consistent with a plane limping along at only 325 knots.

But Mr Farrar said that the group of independent experts with whom he was working had assumed a speed of 460 to 470 knots. "We are unclear about why they are driving to a relatively slower solution," he said.

Two possible explanations are that the authorities believe the plane travelled farther west before turning south, or that the plane did not follow a straight path on its trip south, Mr Farrar said.

The Australian government has said that it will announce the new search area by the end of this month.