Goh Choon Phung said SIA was "very sorry for the traumatic experience" suffered by those onboard flight SQ321 from Heathrow to Singapore, which made an emergency landing in Bangkok.

A British national who died onboard the flight has been named as 73-year-old Geoff Kitchen from Thornbury, who is suspected to have suffered a heart attack after the aircraft experienced a sudden drop in altitude over the Indian Ocean, dropping more than 6,000 feet (around 1,800 metres) in three minutes.

Eyewitness reports from other passengers suggest those not wearing their belts were ejected from their seats, slamming into the overhead lockers above. Seven suffered critical injuries, and dozens more minor injuries.

Mr Kitchen was among the 211 passengers – 47 of whom were from the UK – and 18 crew onboard. The BBC reports nearly 80 passengers and six members of crew remain in Bangkok where they are being treated for their injuries.

A relief flight carrying the remaining passengers and crew arrived in Singapore during the early hours of Wednesday morning (22 May). A Foreign Office spokesperson told the BBC it was supporting Mr Kitchen’s family and was in contact with local authorities.

"On behalf of Singapore Airlines, I would like to express my deepest condolences to the family and loved ones of the deceased passenger," said Goh in a video message. “We also deeply apologise for the trauma experienced by all passengers and crew members on this flight.

"We are providing all possible assistance and support to them, along with their families and loved ones, during this difficult time. The wellbeing of our passengers and staff is our utmost priority."

Mr Kitchen is understood to have been heading to Singapore with his wife to start a six-week holiday.

Singapore’s Transport Safety Investigation Bureau will investigate the incident said the country’s prime minister Lawrence Wong, pledging to work closely with Thai counterparts. The US has also sent investigators.

SIA has one of the best safety records of any international carrier.