The Laos government said Saturday it was "profoundly saddened" by the deaths of foreign tourists in Vang Vieng, with the toll from a suspected methanol poisoning incident now at six.

A statement posted on its Ministry of Foreign Affairs website said it expressed "sincere sympathy and deepest condolences to the families of the deceased", adding an investigation was underway to find the cause of the incident.

Six tourists died of suspected methanol poisoning after a night out in the Laos backpacker hotspot of Vang Vieng last week.

The two Danish citizens, an American, a Briton and two Australians were among a group of about a dozen foreigners who fell ill shortly after November 12.

Australian officials are pressing Laotian authorities for a full and transparent investigation into what happened.

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 synonymous with backpackers behaving badly at jungle parties but has since re-branded as an eco-tourism destination.

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

No charges have been made, however.

Police in Laos could not be reached for comment on Saturday.

Alcohol tainted with methanol is suspected to be the cause of the deaths.

Methanol is a toxic alcohol that can be added to liquor to increase its potency but can cause blindness, liver damage and death.

On their travel advice websites, UK and Australian authorities have warned their citizens to beware of methanol poisoning while consuming alcohol in Laos.

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© Agence France-Presse