Authorities said four suspects, including an Indonesian national, were arrested earlier this month at a villa on the island.

They are accused of operating a hydroponic marijuana and mephedrone manufacturing laboratory.

The Ukrainian suspects, named only by their initials IV and MV, were in charge of producing and mixing materials to manufacture the drugs, said Wahyu Widada, head of Indonesia's criminal investigation agency.

The Russian suspect identified as KK was a drug marketer under a network called Hydra, he added.

All were charged with drug offences that carry a maximum punishment of the death penalty and a fine of Rp 10 billion ($622,000).

Police confiscated at least 10 kilograms of hydroponic marijuana, 684 grams of mephedrone, and 107 grams of cocaine.

"We also confiscated ecstasy molding equipment by which they attempted to produce the drugs but their production had always been unsuccessful," Wahyu said in the press release.

Police said the Indonesian suspect was also being investigated for an earlier drug lab case in Jakarta.

Indonesia has some of the world's toughest drug laws including the death penalty for traffickers.

There are dozens of traffickers on death row in the country, including a cocaine-smuggling British grandmother and a Philippine woman accused of smuggling heroin.

Earlier on Monday, Bali police said a 49-year-old Australian faces up to 20 years in prison and a fine of more than $600,000 for allegedly consuming and attempting to sell crystal meth.