Thai businessman Srivaddhanaprabha died along with four others when his helicopter crashed and then exploded outside the club's King Power Stadium on Saturday after a Premier League match against West Ham United.

The Air Accidents Investigation Branch said it had recovered the flight data recorder and would remain in the city until the end of the week before transporting the wreckage to its facilities in Farnborough.

"Today, our inspectors in Farnborough will start working on the recorder, which was subject to intense heat as a result of the post-accident fire," according to a statement from the AAIB, which investigates all civil aircraft accidents in Britain.

The cause of the crash remains unclear.

Leicestershire Police said on Twitter that their drone was not in flight when the helicopter left the stadium.

It came down in a car park outside the ground shortly after 7.30pm local time, about an hour after the end the match.

Police named the other victims of the crash as passengers Izabela Roza Lechowiczas, Nursara Suknamai and Kaveporn Punpare, and pilot Eric Swaffer.

The Italian maker of the helicopter, Leonardo SpA, said it was ready to assist the investigation.

Vichai's family, including his son Aiyawatt and wife Aimon, arrived at the stadium on Monday to lay flowers among the mass of tributes already left by the club's supporters.

Hundreds of people had queued since the morning to lay toys, scarves and bouquets to remember the much-loved owner who took over the club in 2010 and oversaw their incredible rise from the second tier to Premier League title winners in 2016.

Players and staff from the club were also at the stadium to pay their respects.

Leicester City's first-team squad had a short training session on Monday morning but the club's fourth round League Cup tie with Southampton, scheduled for Tuesday at the King Power, was postponed because of the accident.

Australian Associated Press