The Bali police have advised tourists and locals to avoid drinking unlabelled drinks after 25 people have died in just one week from drinking arak, a local Balinese alcoholic beverage that contained methanol.

Gde Sugianyar, Bali police spokesman advised Balinese and tourists to avoid unlabelled drinks as a precaution.

“We have been watching and conducting raids across Bali especially arak sellers who sell their liquor from jerry cans. We asked Balinese to stop buying unlabelled arak until we find what exactly caused the deaths,” Sugianyar told Reuters.

The deaths include Rene Puper, 23, from the Netherlands and his Irish girlfriend Rachel Maria Craig, 25. American Rose Johnson, 48, from Phoenix and British grandfather Alan Cole who had been living in Bali for the past 13 years.