An Australian woman detained by Cambodian police on allegations of drug possession may have angered the government by publicly criticising the prime minister, expats in the city of Siem Reap have said.

Hun Sen’s government is sensitive to public criticism with national elections in July already widely condemned as lacking credibility after he banned the main opposition party and jailed political opponents.

The Australian, Rachel Prins, was detained by Cambodian police after they raided her bar, the Soul Train Reggae Bar, in Siem Reap just before midnight on Monday.

The ancient city, home to the temples of Angkor Wat, is a popular tourist destination, and Prins’s bar is one of many on the long-established Little Pub Street.

Reports say five people have been charged with possession and use of illegal drugs.

The group, which included Prins’s Cambodian boyfriend, is alleged to have been in possession of seven packages of marijuana and 25 marijuana cigarettes.

But several posters on the Cambodia Expats Online blog – discussing the arrest under pseudonyms – said Prins’s recent overt and public criticism of the prime minister was ill-advised, and could have been the catalyst for her arrest.

Prins told the Phnom Penh Post two months ago that western tourists were being deterred from visiting by government-led heavy-handed police tactics over parties and pool crawls.

“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.

Australia’s Department of Foreign Affairs and Trade said it is providing consular assistance to an Australian citizen detained in Cambodia. It declined to release more information on privacy grounds.

Hun, a former Khmer Rouge cadre, has ruled Cambodia for more than 30 years. He has been accused of large-scale corruption, enriching his family and cronies, as well as corruption of the criminal justice system, and sustained violence against and persecution of his political enemies.

The UN human rights council heard last month the Cambodian government used the country’s courts to jail political opponents and dissolve opposition parties. Dissidents have been murdered and opposition members of parliament publicly beaten or thrown out of parliament and replaced with members of Hun’s ruling People’s party and other parties.

Hun Sen is widely expected to win July’s national elections, with almost all opposition removed.

His visit to Australia last month for the Australia-Asean summit sparked demonstrations in Sydney, where protesters condemned him as a “thug” with “blood on his hands”.

Australia has had a complicated relationship with Cambodia, with a number of continuing tensions, but also significant interdependency.

An Australian filmmaker, James Ricketson, has been in jail in Phnom Penh for 10 months on charges of espionage after he flew a drone over an opposition party rally, shooting footage for a documentary. He denies the charges, which carry a potential jail term of up to 10 years.

And Australia has criticised the country’s deteriorating democracy. It was one of 45 countries to tell the UN human rights council: “Our previous optimism has been replaced by deep concern about the recent serious decline of civil and political rights in Cambodia. These backward steps include signs of escalating repression of the political opposition, civil society and media.

“For the Cambodian government to retain its legitimacy, any elections must be free, fair and credible.”

However, Australia relies on Cambodia as a partner in its offshore processing policy for refugees.

Australia gave Hun Sen’s government an additional $40m in aid in exchange for agreeing to resettle refugees from Australia’s offshore processing regime on Nauru – at further Australian expense. But the scheme has been a costly failure: only three refugees have been resettled there. Others have gone to Cambodia and then left.