An American citizen has died at a popular adventure spot in Laos where alcohol tainted with methanol has been blamed for a spate of poisonings in recent days.

A methanol poisoning incident in Vang Vieng, Laos, has resulted in six tourist deaths, including citizens from Australia, Denmark, the UK, and the US. A New Zealand citizen was also affected but survived.

Details have been murky over the number of tourists affected and the possible source of the methanol-laced drinks.

A New Zealand citizen poisoned after drinking contaminated alcohol in a popular tourist town in Laos has returned home, authorities said on Monday, as Laos pledged to prosecute those responsible for the incident which has killed six tourists.

Six tourists, including Australians and a British woman, died in Laos, likely from methanol poisoning. The U.S. State Department warns travelers about this risk. The Laos government is investigating the incident and expressed condolences to the victims' families.

A second Australian teenager who fell critically ill after drinking tainted alcohol in Laos has died in a hospital in Bangkok, her family said Friday, bringing the death toll in the mass poisoning of foreign tourists to six.