BOSTON, June 26 — The US Coast Guard is investigating the cause of the undersea implosion of a tourist submersible that killed all five people aboard while diving to the century-old wreck of the Titanic, officials said yesterday.

The announcement comes a day after Canada’s Transportation Safety Board said it was conducting its own investigation into the implosion of the Titan, which has raised questions about the unregulated nature of such expeditions.

"My primary goal is to prevent a similar occurrence by making the necessary recommendations to enhance the safety of the maritime domain worldwide,” Captain Jason Neubauer, the Coast Guard’s chief investigator, said at a press conference in Boston.

The Coast Guard opened what it calls a marine board investigation on Friday, Neubauer said, and is working with the FBI to recover evidence, including a salvage operation at the debris site on the seabed about 488 metres from the bow of the Titanic wreck, about 4km below the surface.

The findings will be shared with the International Maritime Organisation and other groups "to help improve the safety framework for submersible operations worldwide,” Neubauer said.

He said the Coast Guard is in touch with the families of the five people killed, and that investigators are "taking all precautions on site if we are to encounter any human remains.” — Reuters