JAKARTA (AFP) - Two Australians on death row in Bali will be among the next group of prisoners to be executed in Indonesia, an official said Monday, as Jakarta takes an increasingly hard line against drug traffickers.

Attorney General H.M. Prasetyo did not say when or where Andrew Chan and Myuran Sukumaran, the leaders of the so-called "Bali Nine" drug-smuggling gang, would be put to death by firing squad, only that "they will be included" in the next batch.

Indonesia last month executed six drug traffickers including five foreigners, triggering a diplomatic storm as Brazil and the Netherlands - whose citizens were among those killed - withdrew their ambassadors.

Indonesian President Joko Widodo has been a vocal supporter of capital punishment, and had already rejected clemency appeals from Sukumaran and Chan.

The pair were arrested in Bali in 2005 and sentenced to death the following year for attempting to smuggle 8kg of heroin out of the island.

Apart from confirming the men would be in the next group to be executed, the attorney general did not give any further details to reporters, or say who else would be included in the group.

In December Sukumaran lost his appeal for presidential clemency, the last chance by a death row convict to avoid the firing squad.

Chan's appeal was rejected last month, removing the final hurdle for Jakarta to push ahead with executing the pair. Authorities have insisted they be put to death together as they committed their crime together.

On Friday they applied for a fresh judicial review of their cases but the attorney general's office has insisted there are no more legal avenues open to them.

Jakarta said last week it was ready to execute seven foreign drug convicts on death row, including the Australians.

Widodo, known as Jokowi, has shocked rights groups with his support for executions, as they had hoped he would take a softer line on capital punishment.

Australian Prime Minister Tony Abbott has urged Indonesia to show mercy to the pair.

"We were surprised - and dismayed - that Jokowi decided to make the death penalty a signature issue of the early part of his administration," Phelim Kine, deputy director Asia for Human Rights Watch, told AFP.