Eighty-two people have died in two Indonesian provinces after they were poisoned by a batch of bootleg alcohol.

The death toll will certainly rise, with more than 100 people in a critical condition in hospitals around Jakarta and West Java province capital Bandung.

It is suspected to be the worst-ever mass fatality caused by alcohol poisoning in a country where drinkers regularly die from consuming homemade bootleg.

Legal alcohol is heavily taxed and too expensive for most Indonesians.

The high price of spirits has contributed to the popularity of illegal bootleg liquor, including a variety known in Java as "oplosan".

The drink is sold in plastic bags on the street and can contain almost anything — from traditional herbal drinks to cheap wine, energy drinks and sometimes home-brewed liquor that contains fatal amounts of methanol.

Patients have been arriving at Bandung's hospitals since the weekend. ( ABC News )

Methanol or methyl alcohol is a poison that is produced in the brewing process. Commercial alcohol producers take care to separate methanol from their products as it can be fatal in tiny amounts.

Bootleggers are not so careful, and it regularly kills drinkers in poorly-regulated markets like Indonesia and Thailand.

The illegal spirits were sold in different roadside stalls and stores around Jakarta and Bandung — but police suspect the deadly alcohol all came from the same original batch.

Police have raided four outlets selling spirits and confiscated bottled alcohol as well as spirits stored in large plastic drums.

So far six people have been arrested for selling the deadly oplosan and police are searching for at least two more suspects.

Police raided bootleg alcohol sellers. ( ABC News )

In Bandung, patients have been arriving at the city's hospitals since the weekend.

Some of the victims were already unconscious and some had been partially-blinded by the moonshine.

More than 100 victims have come to the city's Cicalengka Public Hospital, its director Yani Sumpena Muchtar said.

"The conditions of which these patients arrived in are varied — from headaches, stomach ache, throwing up, blurred vision to unconsciousness," the doctor said.

"At the moment, 29 people are in critical condition, 11 are being treated in regular wards, and 31 people have died here."