Citing an unnamed senior US Navy official, the Journal said the implosion was recorded shortly after the Titan went missing on Sunday by a secret acoustic monitoring system designed to detect submarines.

"The US Navy conducted an analysis of acoustic data and detected an anomaly consistent with an implosion or explosion in the general vicinity of where the Titan submersible was operating when communications were lost," the official told the Journal.

On Thursday, the US Coast Guard said it had found wreckage of the submersible near the remains of the Titanic, which sits 3,800 meters (12,400 feet) under the sea.

The announcement ended a four-day multinational search-and-rescue operation, with officials telling reporters that analysis showed debris found on the seafloor was consistent with the implosion of the sub's pressure chamber.

The craft's five passengers are presumed dead, according to OceanGate Expeditions, which operated the submersible.