The money belonged to Thai businessman Chukamon Khammat.

Chukamon wrote a letter, published on Facebook on July 9 on a road safety community site, describing the good deed of the taxi driver, later identified as Lee Koh Wee.

He said he had been drinking with his business partners at Clarke Quay and returned at about 4am in the taxi to Marina Bay Sands, where he had been staying.

He realised he had left his bag containing the money which had been given by investors in Singapore for a business scheme in Thailand.

He was about to lose any hope of recovering the money when the driver came to the hotel at 5am and handed him the bag with the money intact.

Straits Times reported that the taxi driver only spotted the bag left by his passenger when he was filling up at a petrol station and was shocked to see the huge amount of money.

Chukamon offered the taxi driver S$1,000 as a reward. In his letter of appreciation, he said the taxi driver was declared bankrupt in 2014 and had only just recently become a taxi driver.