After Titanic director James Cameron accused OceanGate Expeditions of ignoring safety warnings, former business partner of the Titan submersible pilot Stockton Rush, Guillermo Soehnlein, Friday said that they put safety first when they co-founded their deep-sea exploration company.

Guillermo Soehnlein, who started OceanGate with Rush before leaving the company in 2013, said he was not involved in the design of the Titan submersible, but denied that his old friend ignored safety concerns.

"He was extremely committed to safety and was also extremely diligent about managing risks, and was very keenly aware of the dangers of operating in a deep ocean environment," Soehnlein told  Britain's Times Radio.

"So that's one of the main reasons I agreed to go into business with him in 2009," he added.

This comes as James Cameron has accused OceanGate Expeditions of ignoring safety warnings after Rush and four other people were lost in a catastrophic implosion while descending to the shipwreck.

Soehnlein noted that Cameron himself had conducted many submersible descents, more than 30 to the Titanic site in the North Atlantic, and to the Earth's deepest point in the Pacific Mariana Trench.

"I think he was asked about a similar risk and he said, 'look, if something happens at that depth, it will be catastrophic in a matter of microseconds'," Soehnlein told the media.

The US Coast Guard Thursday confirmed that all five passengers aboard the missing submersible owned by OceanGate have died due to a "catastrophic implosion".

The submersible was diving 13,000 feet to view the Titanic which is located on the ocean floor.

Tour organizer OceanGate Expeditions said in a statement: "We now believe that our CEO Stockton Rush, Shahzada Dawood and his son Suleman Dawood,  Hamish Harding, and Paul-Henri Nargeolet, have sadly been lost."