PHNOM PENH - Speaking at an event to celebrate the listing of Cambodia's latest World Heritage site, Prime Minister Hun Sen used the opportunity to quash speculation about his health.

"Am I the real Hun Sen, nieces and nephews?" he asked, addressing a 10,000 strong crowd which has gathered at the Olympics Stadium here on Monday (July 17).

He said the listing of Sambor Prei Kuk archaeological site as a world heritage site would greatly contribute to the development of the country's tourism industry, reported Xinhua news agency. Cambodia's newest Unesco Word Heritage site is about 200 km north of Phnom Penh and 170km south-east of Siem Reap.

Mr Hun Sen said the listing of the 7th century pre-Angkorian temples as a World Heritage site could lure tourists to Kompong Thom province and create more jobs for local residents. He also posted a video of the ceremony on his Facebook page.

Last week, an overseas government critic who goes by the moniker Cham Chany claimed on his Facebook page that the prime minister had gone to Singapore for medical treatment but not appointed any acting leader in his absence, reported Cambodia Daily.

The Facebook user, who has had runs-in with the Hun Sen family, said an anonymous source had informed him that Mr Hun Sen was concerned about the loyalty of ruling party members.

Mr Hun Sen's noticeable absence from political activities in recent weeks also fuelled speculation over his health.

But the 64-year-old leader has taken to the social media to counter the rumours, posting on his Facebook page video selfies and photographs of a casual Sunday drive.

"If the prime minister lost his position like they said, surely this country would be plunged into chaos," he said in a video posted to his Facebook page on Saturday. The video clip shows him in the seat of a vehicle moving through a city he said was Phnom Penh.

"This very bad rumour should be eliminated via my video clip that shows I am living, travelling like normal, in traffic jams like any other," he said.

The next day, the government-aligned Fresh News posted a photo album of the prime minister driving along Hun Sen Boulevard, posing alongside cars and even taking the wheel of an old Toyota sedan from a bewildered-looking family apparently in the area for a driving lesson.

Last week, he had posted photos of him dining with Royal Cambodian Armed Forces deputy commander Kun Kim, Land Management Minister Chea Sophara, tycoon Kith Meng and his middle son Hun Manith.

"Wherever I am, I still have the ability to lead the country's affairs, especially to crack down on the chaos caused by a group of gangsters, extremists and a group of traitors," he said in the post.

"If you want to know, let's try it."

He also uploaded pictures of him a visiting a shopping mall with several members of his family.

"Do I need to tell all the people, especially a group of gangsters, that I was here or there?" he wrote, without disclosing his location. Some netizens said the location was Singapore's ION Orchard mall.

But ruling Cambodian People's Party spokesman Sok Eysan said Mr Hun Sen never left the country.

"He is fine," Mr Eysan was quoted as saying by the Cambodia Daily.

Mr Hun Sen was briefly hospitalised in Singapore last year and in May this year.w