Text messages from two Danish backpackers who died in a mass poisoning in Laossuggest the pair had been vomiting blood for 13 hours.

Anne-Sofie Orkild Coyman, 20, and Freja Vennervald Sorensen, 21, were later discovered dead at Nana Backpackers in Vang Vieng, Laos.

The two women reportedly drank from a batch of alcohol allegedly laced with methanol. This same tainted batch has been linked to four additional deaths, including Australian teenagers Holly Bowles and Bianca Jones, and put 11 foreigners in critical condition, including a Kiwi.

Nana Backpacker hostel, Laos.

The young women from Roskilde, Denmark were staying in Vang Vieng, Laos during a backpacking trip around southeast Asia. They were planning to meet a Belgian man they met earlier on their trip.

The pair reportedly texted this man to say they had been vomiting blood for several hours after they consumed the methanol-laced alcohol.

A friend of the Belgian backpacker then took to social media to share a warning.

“The past few days I have been busy with a Belgian friend looking for two girls he travelled with,” the post, also shared to Reddit, read.

“For more than 72 hours, no contact could be made while they had agreed to meet in Vang Vieng. The strange thing was that their last message was that they had both been vomiting blood for 13 hours … They have both since died.”

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According to local police, Sorensen and Coyman had drinks at their hostel bar on November 12 then continued drinking at other venues. They returned to their room around midnight but remained inside after that.

They were found unconscious on their bathroom floor by hostel staff around 6pm the following day. Although rushed to the hospital, both were declared dead by 3.30am on November 14.

Anne-Sofie Orkild Coyman, right, and Freja Vennervald Sorensen with local children in Vietnam. Photo / via Instagram

The same toxic batch of alcohol is thought to have also poisoned a Kiwi tourist. Today, a Ministry of Foreign Affairs spokesperson provided an update on the tourist and how they were getting home.

“The New Zealand Embassy in Bangkok [which has responsibility for Laos] has been providing assistance to one New Zealander who we believe to have been poisoned with methanol in Laos,” she said.

Mfat has updated its travel advisory for Laos following several cases of suspected methanol poisoning after consuming alcoholic drinks.

Two 19-year-old Melbourne travellers who stayed at the same hostel have also died from methanol poisoning.

Freja Vennervald Sorensen seen drinking while the women were in Bangkok before travelling to Nana Backpackers in Vang Vieng, Laos. Photo / via Instagram

Holly Bowles and Bianca Jones reportedly consumed cocktails that contained lethal amounts of methanol in Vang Vieng. Staff at Nana Backpackers Hostel claim they drank at the bar on November 11 and then went to another venue.

The following day, they stayed in their room but later told staff they were struggling to breathe and needed urgent medical attention, according to Melbourne newspaper Herald Sun.

Why would a bar use methanol in drinks?

Methanol is often found in drinks when the intention is to cut costs, according to emergency specialist and toxicologist Dr Paul Gee.

“The most likely way that a tourist is likely to get methanol mixed in with their drinks is if they have a cocktail for a mixed drink in a bar in one of these countries,” Gee previously told RNZ.

“In those countries, bars often substitute commercially produced alcohol for bootleg alcohol because it’s cheaper.”

Consuming methanol may initially provide a high similar to how you feel after drinking alcohol but the symptoms quickly take a turn.

“When the body ingests methanol, it initially thinks it’s like ethanol, you’ll feel intoxicated, perhaps slightly high, but as the body converts the methanol into an acid you’ll get increasingly unwell,” Gee said.