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The US Coast Guard has just tweeted confirming that a Canadian P-3 aircraft "detected underwater noises in the search area".

This is the first official confirmation from search authorities of the information being reported by US media, although they did not specify "banging" sounds.

As a result of the pick-up, the US Coast Guard said they had relocated operations. So far those searchers "have yielded negative results".

The internal US Department of Homeland Security memos being reported say the underwater banging sounds could be heard for hours.

After the inital pick-up by a Candian aircraft, additional sonar was deployed to the area four hours later where "banging was still heard".

CNN is also reporting an updated memo sent Tuesday night, which suggested more sounds were picked up.

“Additional acoustic feedback was heard and will assist in vectoring surface assets and also indicating continued hope of survivors,” said the second memo according to CNN's report.