Six foreign tourists have died after a suspected mass methanol poisoning from drinking tainted alcohol at a backpacker hotspot in Laos.

Australian Holly Bowles, 19, became the incident's latest fatality on Friday when she died in a Bangkok hospital surrounded by family. Bowles’ best friend, Bianca Jones, died as a result of the poisoning on Thursday.

A British lawyer identified in reports as Simone White also died, and the UK foreign office said it was "supporting the family of a British woman who has died in Laos."

Two Danish citizens and an American also died, officials said, after what media described as a night out in Vang Vieng where they drank possibly tainted alcohol.

The group of about a dozen tourists became ill after going out on November 12, according to British and Australian media.

Bowles and Jones, both aged 19 from Melbourne, became unwell while staying at Vang Vieng's Nana Backpackers Hostel last week, Australian media reported. 

The women drank at the hostel's bar before they went out for the evening, the Sydney Morning Herald reported.

They failed to check out on November 13, when hostel staff rushed the pair to the hospital.

The Facebook and Instagram pages of the hostel had been deactivated as of Thursday and it was no longer taking bookings on websites.

AFP was unable to reach the hostel for comment. 

'Unimaginable time'

The Vietnamese manager of the hostel has been detained for questioning, the Laos tourist police told AFP.

No charges have been made, however, as police are still "investigating," an official said, speaking on condition of anonymity.

In a statement on its website, Laos' Ministry of Foreign Affairs said Saturday it expressed "sincere sympathy and deepest condolences to the families of the deceased", adding an investigation was underway.

The US State Department also confirmed the "death of a US citizen in Vang Vieng, Laos," and said it was "closely monitoring the situation and providing consular assistance."

It did not give details on the date or cause of death.

New Zealand's embassy in Bangkok said it had been contacted by one of its citizens "who was unwell and may be a victim of methanol poisoning in Laos".

Vang Vieng has been a fixture on the Southeast Asia backpacker trail since Laos' secretive communist rulers opened the country to tourism decades ago.

The town was once notorious for backpackers behaving badly at jungle parties and has since re-branded as an eco-tourism destination. Alcohol tainted with methanol, a toxic alcohol usually used in industrial and household products like antifreeze, is suspected to be the cause of the deaths.

It can be added to liquor to increase its potency but can cause blindness, liver damage and death.

On their travel advice websites for Laos, UK and Australian authorities warn their citizens to beware of methanol poisoning while consuming alcohol in the country. 

In neighbouring Thailand, at least six people died and more than 20 were hospitalised after drinking methanol-laced bootleg alcohol in August.

But in Vang Vieng, business seemed to be going on as usual.

"I heard the news but everything is normal here," Michael, a manager at Vangvieng Rock Backpacker Rooftop Hostel told AFP on Friday, asking to use only one name.

"The high season is about to start, so we are welcoming more tourists every day." 

"There are still many tourists in town, and they go partying," a receptionist at Vang Vieng Chill House Hostel told AFP.