In Mexico, 111,896 people are currently registered as missing in the interior ministry's official database, a number that does not include the many more people who went missing and were later found dead.

Selangor police chief Hussein Omar Khan says a missing persons inquiry has been opened which will investigate any element of crime, including kidnapping.

The somber announcement ends a multinational search-and-rescue operation that captivated the world since the tiny tourist craft went missing in the North Atlantic four days ago.

Even if the submersible is located, retrieving it presents huge logistical challenges, given the extreme conditions thousands of metres below the surface.

The fate of the submersible and those aboard remains a mystery as search teams from the US, Canada and France mount an intensifying search in an area of open sea larger than the state of Connecticut.

The vessel has a range of 96 hours for a crew of five, and might have had 70 or more hours of remaining oxygen as of Monday afternoon.

The 39 people on board - 17 Chinese crew members, 17 Indonesians and five from the Philippines - are missing, reports say.

Investigators previously drew no conclusion about what happened aboard the flight, but did not rule out the possibility that the aircraft had been deliberately taken off course.

From chatbots to mass texts, social media to online guides, tech has transformed the painful hunt that thousands of Mexicans must undertake to find a ransomed relative.

This is the first time the mainland China-based boutique bank has given a reason for the disappearance of its founder Bao Fan, though no details about the investigation were shared.

Bao Fan, who is also executive director of the bank, is a major figure in the Chinese tech industry and has played a key role in the emergence of various domestic internet startups.

The man has been on a wanted list for allegedly running away while awaiting admission to quarantine.