Indian police say at least 50 people have died and another 50 have been sickened after drinking tainted liquor in two separate incidents in India's remote northeast.

Police officer Julie Sonowal says the victims were mostly tea plantation workers in the Golaghat and Jorhat districts in Assam state.

The workers consumed tainted liquor laced with methyl alcohol, a chemical that attacks the central nervous system, on Thursday and started falling unconscious. They were rushed to hospitals and the death toll had increased to 50, Sonowal said.

The owner of a brew-making unit and four others have been arrested.

Deaths from illegally brewed alcohol are common in India because the poor cannot afford licensed brands. Illicit liquor is cheap and often spiked to increase potency.