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The US Coast Guard on Thursday said a debris field was discovered within the search area by a remotely operated vehicle near the Titanic.
Experts within the unified command were evaluating the information, the Coast Guard said.
A remotely operated vehicle deployed from a Canadian vessel to the ocean floor discovered the debris field.
Another robot from a French research ship was also sent diving toward the seabed to search for signs of the 22-foot (6.7-metre) Titan submersible.
The desperate search for the submersible near the wreck of the Titanic entered a critical juncture on Thursday when air was expected to run out for the five people aboard, but officials vowed to continue scouring the remote North Atlantic.
The van-sized Titan, operated by US-based OceanGate Expeditions, began what was to be a two-hour descent at 8:00 am (1200 GMT) on Sunday but lost contact with its support ship.
The submersible set off with 96 hours of air, according to the company, which means the oxygen would be exhausted by Thursday morning, assuming the Titan is still intact.
Precisely when depends on factors such as whether the craft still has power and how calm those on board are, experts say.
Rescuers and relatives of the Titan's five occupants took hope when the US Coast Guard said on Wednesday that Canadian search planes had recorded undersea noises using sonar buoys earlier that day and on Tuesday.
But remote-controlled underwater vehicles searching where the noises were detected did not yield results, and officials cautioned the sounds might not have originated from the Titan.