But the US Navy has since issued a statement calling Mr Dean's comments "speculative and premature".

"The US has been working cooperatively with our Malaysia, Australian and international partners for more than two months in an effort to locate MH370," a spokesman said.

"Mike Dean's comments today were speculative and premature, as we continue to work with our partners to more thoroughly understand the data acquired by the towed pinger locator.

"As such, we would defer to the Australians, as the lead in the search effort, to make additional information known at the appropriate time."

Mr Dean told CNN it was not possible to absolutely exclude that the pings came from the black boxes, but there was no evidence now to suggest they did.

Yesterday afternoon, Bluefin-21 completed its last mission searching the remaining areas in the vicinity of the acoustic signals detected in early April by the Towed Pinger Locator deployed from ADV Ocean Shield, within its depth operating limits.

The data collected on yesterday's mission has been analysed. As a result, the Joint Agency Coordination Centre can advise that no signs of aircraft debris have been found by the Autonomous Underwater Vehicle since it joined the search effort.

Since Bluefin-21 has been involved in the search, it has scoured over 850 square kilometres of the ocean floor looking for signs of the missing aircraft.

The Australian Transport Safety Bureau (ATSB) has advised that the search in the vicinity of the acoustic detections can now be considered complete and in its professional judgement, the area can now be discounted as the final resting place of MH370.