Cambodian Prime Minister Samdech Techo Hun Sen has been fined by a traffic police for not wearing a helmet during his motorbike ride last week in southwestern Koh Kong province and after he publicly apologized for his mistake.

According to a traffic ticket slip, dated on June 18, issued by First Lieutenant Sun Nem, traffic police officer in the province's Sre Ambel district, he had monitored a motorbike rider named Samdech Techo Hun Sen who had violated article 6 of the traffic law and was fined 15,000 riel (3.75 U.S. dollars).

"Please go to pay the fine in Phnom Penh," he said.

Hun Sen wrote on his Facebook page late Wednesday that he accepted the fine and would pay for himself and also the owner of the motorbike who would also be fined the same amount.

"I have known in advance that even though I apologised publicly, the police still fined me because I had made a mistake," he said.

He added that the parliamentary immunity, which is enshrined in the kingdom's constitution, and other laws do not pardon any lawmaker or prime minister from being penalized for breaking the traffic law such as riding a motorbike without wearing a helmet or having a number-plate.

"I appreciate Koh Kong province's Sre Ampel district police who enforce the law without discrimination and without fear of the powerful people including the prime minister," he said.

The fine came after Hun Sen traveled to Koh Kong province on June 18 and he unexpectedly visited a motor-taxi driver on the road side and rode the motorbike with the motorbike's owner for fun for about 250 meters without wearing a helmet.

On Monday, the prime minister publicly apologised for his mistake after Facebook users mocked him for failing to wear a helmet when riding a motorbike.