At a press conference announcing six drug felons would be executed on January 18, Indonesian Attorney-General H.M. Prasetyo said the government was waiting on the outcome of Chan's clemency appeal before executing Myuran Sukumuran.

Although no Australians are in the first group of convicts on death row to be executed on January 18, Mr Prasetyo warned the second batch of executions would also prioritise those sentenced to death for drug offences.

This means Sukumuran and Chan could face the firing squad within months if Chan loses his appeal.

"When a crime is committed by more than one person, the execution must be conducted at the same time," Mr Prasetyo said. "So Myuran will wait for his turn."

Chan and Sukumuran were sentenced to death by firing squad in 2006 for being involved in a conspiracy to import 8.2 kilograms of heroin from Bali to Australia.

They based their clemency bids on the strong efforts they have made at rehabilitation since they were jailed in Kerobokan prison in 2005.

Mr Prasetyo also said the Australian government had not put pressure on Indonesia over the Bali Nine cases nor asked it to consider lighter sentences.

Sukumuran learned last week that his clemency appeal had been rejected by Indonesian president Joko Widodo. Chan is yet to receive a response from his plea.

Mr Prasetyo denied that diplomatic relations with those countries whose citizens were to be executed would be affected.

"They all understand because drugs crime is the common enemy so I think each foreign country will respect Indonesia's legal system."

Mr Prasetyo said he realised there were pros and cons of capital punishment but it remained Indonesia's policy.

"When the death sentence is handed down, it should be carried out," he said.

Mr Prasetyo said drug crimes were particularly bad, which is why the maximum penalty was death.

"The drugs network has spread all over the country, not only in big cities but also in villages," he said.

"It has many victims, mostly youngsters at their most productive age. Forty to fifty people in Indonesia die every day because of drugs."

Indonesia's method of execution has not changed since a decree signed by its first president in 1964. Prisoners are woken in the middle of the night in their isolation cells in secret locations. They are offered blindfolds, and asked if they would like to stand, sit or lie down before being executed by a firing squad.

Mr Prasetyo said those to be executed had been notified on Wednesday in accordance with regulations that they have to be given three days' notice.

Those to be executed on Sunday are Rani Andriani, an Indonesian, Marco Archer Cardoso Moreira from Brazil, Tran Thi Bich Hanh from Vietnam, Namaona Denis from Malawi, Daniel Enemuo from Nigeria and Ang Kiem Soei, who was born in Papua but whose nationality is unclear.

Five would be executed on the penal island of Nusakambangan, know as Indonesia's Alcatraz.

The sixth is to be executed in Boyolali in Central Java.

With Karuni Rompies