A Canadian P-3 plane - using sonar buoys - heard underwater sounds which US Navy experts are now analysing.
Crews have been exploring the source of the noise on Wednesday in a remote part of the North Atlantic.
There may be as little as a day's worth of oxygen left on the vessel if it remains intact.
The US Coast Guard did not provide further details on what the noises could be. According to an internal US government memo seen by several media outlets, banging was heard at 30-minute intervals on Tuesday.
Additional sonar was used four hours after the sounds were first detected and noises could still be heard, officials said.
Remotely operated vehicles (ROVs) have been deployed to the area but have not found anything further.
A Canadian P-3 plane - using sonar buoys - heard underwater sounds which US Navy experts are now analysing.
Crews have been exploring the source of the noise on Wednesday in a remote part of the North Atlantic.
There may be as little as a day's worth of oxygen left on the vessel if it remains intact.
The US Coast Guard did not provide further details on what the noises could be. According to an internal US government memo seen by several media outlets, banging was heard at 30-minute intervals on Tuesday.
Additional sonar was used four hours after the sounds were first detected and noises could still be heard, officials said.
Remotely operated vehicles (ROVs) have been deployed to the area but have not found anything further.