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.

The U.S., Australia and U.K. have issued warnings for travelers in Vang Vieng after several tourists died in a suspected methanol poisoning outbreak.

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.