Laotian police have detained the manager and owner of a hostel where two teenage Australian tourists stayed who were poisoned by tainted alcohol, one fatally, in a case that appears to have claimed the lives of at least five people.

An officer at Vang Vieng's Tourism Police office, who refused to give his name, told The Associated Press on Friday that a “number of people” had been detained in the case but that no charges have yet been filed.

Staff at the Nana Backpacker Hostel, which was still operating but not accepting new guests, confirmed that the manager and owner were among those taken in for questioning.

Tourist police offices are common in Southeast Asia and are set up specifically to help with incidents involving tourists and other foreigners.

The US State Department on Friday issued a health alert for citizens traveling in Laos, warning of “suspected methanol poisoning in Vang Vieng, possibly through the consumption of methanol-laced alcoholic drinks", following similar alerts from other countries whose citizens were involved.

Australia's prime minister announced Thursday that a 19-year-old citizen had died in a Thai hospital where she had been evacuated for emergency treatment, and that her friend remained in a hospital "fighting for her life".

A 28-year-old British woman also died from suspected methanol poisoning in Laos, the British Foreign Office said.

An American and two Danish tourists also died, though specifics about the causes of death have not been released.

Laos is a one-party communist state with no organised opposition and the government keeps a tight lid on information. In this case, officials have released almost no details.

The Foreign Ministry has refused to comment, and in Vang Vieng the small hospital where some of the victims are believed to have been treated initially referred all questions to the town's health office on the hospital grounds. The town health officials refused to comment, saying they lacked proper permission.

Methanol is sometimes added to mixed drinks at disreputable bars as a cheaper alternative to ethanol, but can cause severe poisoning or death. It is also a byproduct of poorly distilled homebrew liquor, and could have found its way into bar drinks inadvertently.

Landlocked Laos is one of Southeast Asia’s poorest nations and a popular tourist destination. Vang Vieng is particularly popular among backpackers seeking partying and adventure sports.

Neil Farmiloe — a New Zealander who owned the Kiwi Kitchen restaurant in town — said a lot of his customers were very worried about the incident.

“I think it’s never happened before, so it is hopefully just a one-off incident," said Farmiloe, who has lived in Vang Vieng for 20 years.

"It’s very sad all around. I’m sure nobody intended to cause injury, but it’s happened.”

It has been more than a week now since the two 19-year-old Australian women fell ill on November 13 following a night out drinking with a group.

They failed to check out from the Nana Backpacker Hostel as planned and were found sick in their room and then taken to Thailand for emergency treatment. One, Bianca Jones, died this week while her friend, Holly Bowles, remains in critical care.

Thai authorities confirmed that Jones had died by "brain swelling due to high levels of methanol found in her system".

Duong Duc Toan, the manager of the Nana Backpacker Hostel, told the AP the day before he was detained that the two women had joined other guests for free shots of Laotian vodka on the night in question, before heading elsewhere and returning in the early hours of the morning.

Britain's Foreign Office said 28-year-old Simone White had also died of suspected of methanol poisoning in Laos.

New Zealand’s Foreign Ministry said one of its citizens was sickened in Laos and was a possible victim of methanol poisoning.