Five of the nine Australians arrested earlier this week in Bali on drugs charges could face the death penalty, Indonesian police have said.
Bali's anti-drugs chief Colonel Bambang Sugiarto said alleged ringleader Andrew Chan and four others were likely to face serious trafficking charges.
If found guilty, they could be given the death penalty or life imprisonment.
The other four detainees are likely to face lesser charges, Mr Sugiarto told the Australian news channel ABC.
The nine Australians were arrested on Sunday night for reportedly trafficking heroin on the Indonesian island of Bali.
Five were detained at Bali's airport, four of them reportedly carrying heroin strapped to their bodies as they were trying to board a flight.
The other four were arrested in a nearby hotel, where police also found a small quantity of drugs, as well as scales and other evidence.
Andrew Chan, aged 21, and four defendants allegedly caught acting as couriers are those likely to face the most serious charges, Mr Sugiarto said.
The arrests follow a 10-week investigation involving both Australian and Indonesian police.
Indonesia has increasingly become a transit route for drug traffickers, and courts across the country have toughened up on offenders in recent years, sentencing several foreigners to death for serious drugs offences.