Instead, the two friends are now dead after collapsing within days of each from what appears to be some sort of mystery illness.

Canadian-born Cathy Huynh, 26, and American Karin Joy Bowerman, 27, fell ill while visiting the coastal city of Nha Trang last week.

Ms Bowerman, who suffered serious respiratory failure and zero blood pressure, was taken to the Khanh Hoa Province General Hospital by her friend last Monday.

Two days later, Ms Huynh, also fell ill and was treated for shock at the same hospital before suffering cardiac arrest and passing away.

The women, who were sharing a room at the Son and Daughter guesthouse, suffered agonising deaths and authorities are speculating the pair may have been poisoned, the Daily Mail reported.

But local police told the Tuoi Tre News the pair may have died after drinking too much alcohol, a claim rejected by the women’s families.

It is not yet known if autopsies have been completed.

The tragedy echoes a case in Thailand last year when a town popular with Australian tourists, suffered a spate of mysterious tourist deaths.

Four tourists and a Thai tour guide died in the hill town of Chiang Mai in Northern Thailand over a five-week period.

Authorities who investigated the deaths at the time claimed they were a coincidence