According to the forum, between 20 and 30 police officers visited the bar for about three hours on Monday evening and questioned patrons before taking some of them away for further questioning.

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In a discussion about the arrests, it is suggested that Ms Prins may have drawn attention to herself – and occurred the wrath of Cambodian authorities – by making comments reported in the Phnom Penh Post that were mildly critical of Cambodian Prime Minister Hun Sen.

"[Prime Minister] Hun Sen is shaking hands with the Chinese, saying ‘America, we don’t need you’, but businesses here need Westerners," the Post quoted her as saying.

Cambodia is ruled with an iron fist by the former military strongman, who has in the past 12 months arrested senior members of the main opposition parties ahead of July elections.

The Soul Train Reggae Bar’s Facebook page features photos of several people smoking what appears to be marijuana.

There are also multiple pictures on the bar's Facebook page of a woman who looks identical to Ms Prins but who is tagged under the name "Pixie Rose".

A separate video posted on Facebook by a Cambodian police officer appears to show police descending on the bar and conducting the raid on Monday evening.

It stated that police were on the scene to crack down on the use of addictive drugs and that the officials in attendance included the deputy police commissioner in charge of fighting crime in Siem Reap, the director of the provincial immigration office, the director of the anti-drug office and a deputy prosecutor.

In the video, the deputy police commissioner can be heard saying in Khmer “we don’t know who is who yet” but that the police had some evidence of drugs on site already.

Fairfax Media has tried to contact Ms Prins but has been unsuccessful.

However, Fairfax Media has spoken to people in Siem Reap who know some of the people detained. They say that at least some of the Australians have already been released by police.

However, several are still being questioned.

Siem Reap is a popular destination for backpackers travelling to Cambodia, with a lively bar and restaurant scene. It also serves as the gateway to the historic temples at Angkor Wat.

In February, a Cambodian court kicked seven Westerners out of the country, weeks after they were accused of "singing and dancing pornographically" at a Siem Reap party.

Cambodia does not enforce the death penalty for illegal drug use but it still has strict drug laws, even for so-called soft drugs such as marijuana.