Sabrina Dawood - the sister of Pakistani businessman Shahzada Dawood, 48, who is a passenger along with his 19-year-old son Suleman - acknowledged the global interest in finding her relatives.

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Speaking to Sky News she said: "We are deeply grateful for the efforts of news agencies during this difficult time; your constant coverage of the missing Titan submersible is undoubtedly playing a large role in the world's ability to access relevant updates on the matter.

"At this time, the Dawood family's sole focus is the rescue of our beloved Shahzada and Suleman Dawood and we are unable to address any questions or comments at the moment.

"We trust that the family will be granted privacy as we deal with this crisis.

"May Shahzada and Suleman return to us safe and sound.

"We are sure they would be as moved as we are by the support of the global community during this period of difficulty."

The Dawoods belong to one of Pakistan's most prominent families whose firm invests across the country in agriculture, industries and the health sector.

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Both Shahzada and Suleman Dawood are British citizens.

The UK-based businessman is also a trustee at the SETI Institute - a Silicon Valley non-for-profit working in space exploration.

The Dawoods are two of five passengers on the small submersible operated by OceanGate - a US-based company which offers crewed submersibles for industry, research and exploration.

Other passengers include British billionaire Hamish Harding, 58, OceanGate Inc CEO and founder Stockton Rush and Paul-Henri Nargeolet, a former commander who served in the French Navy for 25 years.

Tickets for an expedition such as this cost $250,000 (£195,000) for an eight-day trip including dives to the wreck.

Contact with the vessel was reportedly lost about an hour and 45 minutes after it submerged on Sunday in the Atlantic.

The remote location and depth are making the rescue mission particularly challenging.

US and Canadian ships and planes are involved, but it remains unclear whether the Titan is still underwater or had surfaced and was unable to communicate.

Dr David Gallo, who describes the Titan's pilot, Mr Nargeolet, as his "best friend", said the timeline suggests something happened "mid-water".

The worst case scenario is "probably a collapse - a catastrophic implosion of the sub itself which would be horrific", Dr Gallo told Sky News.