Families at bedsides of Holly Bowles and Bianca Jones in Thailand ...

The parents of two Melbourne 19-year-olds are at their bedsides in separate Thai hospitals as the women fight for their lives after drinking tainted alcohol.

Holly Bowles and Bianca Jones were staying at a backpacker hostel in Vang Vieng, a popular party town north of the Laotian capital, Vientiane.

According to the owner of the Nana Hostel, they had been out drinking at a nearby bar last Tuesday night and, in the early hours of Wednesday morning, were taken to a hospital in Vientiane after falling ill.

Holly Bowles's family say they are in a state of disbelief about what has happened. (Facebook)

It is understood at least two Danish women in their 20s have died, and at least 10 have fallen ill after drinking the tainted alcohol.

A statement from the Danish Ministry of Foreign Affairs said: "The Ministry of Foreign Affairs can confirm that two Danish citizens have passed away in Laos. For reasons of confidentiality in personal matters the Ministry of Foreign Affairs has no further comments."

Ms Bowles' uncle said her family was struggling to come to terms with what had happened.

Speaking from Melbourne, Dale Bowles said Holly's parents were maintaining a bedside vigil at the Bangkok Hospital in Thailand.

Dale Bowles said the family was struggling with shock and disbelief. (ABC News)

"It's so difficult when you're so far away," Mr Bowles said.

"There's just a sick feeling in your stomach that just doesn't go away.

"We're a small family, we're a tight family, we come together in tough situations and there's none tougher than this."

The friends were on a backpacking holiday in Laos. (Reuters:  K Yoganand/WWF)

Mr Bowles said the family was holding out for positive news as his niece remained on life support.

"It's just a day-by-day process at the moment," he said.

"At this point … all we can ask her to do is just keep fighting."

The family of Bianca Jones said they were praying for her recovery. (Supplied)

The family of Bianca Jones is also by her bedside at the Udon Thani Hospital, which is in Thailand's north, near the border with Laos.

"Our beautiful Bianca was on a dream getaway with her best friend Holly," the family said in a statement.

"They were filled with joy and had such incredible adventures ahead of them, travelling through Asia.

"We are here by Bianca's bedside praying for her."

The owner of the Nana Backpacker Hostel denies the allegedly poisoned drinks were served there. (Facebook: Nana Backpacker Hostel)

A spokesman for the Department of Foreign Affairs and Trade said the government was providing consular assistance to two Australians and their families in Thailand.

"Our thoughts are with them at this deeply distressing time," he said.

"Owing to our privacy obligations we are unable to provide further comment."

Duong van Huan, the owner of Nana Hostel, said he was sure the poisoned drinks were not sold at his bar, saying none of the other hostel guests fell ill.

He was adamant he never added methanol to the drinks at the bar.

"The police in Vang Vieng and Vientiane already came to the hostel to check, the shop (where) we buy the vodka, check the shop [where] we buy the whisky."

"We don't do anything wrong, for sure."

Hostel owner Duong van Huan said the police had already checked his bar and the shop where he buys his alcohol. (ABC News)

Mr van Huan said he had been in business in Vientiane and Vang Vieng for almost 11 years, and it was the first time something like this had happened.

"I really take care of all of the customers [who] stay with our hotel and our hostel."

Methanol is a clear liquid chemical that is often deliberately and illegally added to alcoholic beverages as a cheaper alternative to ethanol.

Consuming even a small amount can be fatal.

Other travellers have posted warnings on social media about possible methanol poisoning in Vang Vieng.

Victoria's Tourism minister Steve Dimopoulos said the state government was waiting to hear more details about the circumstances behind the apparent poisoning.

"Our hearts go out to them, to their families," he said.

"What was meant to be a beautiful holiday full of memories has ended in absolute tragedy."