Two Australian drug traffickers will be transferred this week to an Indonesian high-security prison before their execution by firing squad, with several other foreigners to follow, the attorney-general's office said Monday.

Australian Prime Minister Tony Abbott vowed earlier to pursue all legal options to save Andrew Chan and Myuran Sukumaran, both in their early 30s, amid a claim that the death penalty judges had asked for bribes in their original trial.

Chan and Sukumaran, ringleaders of the so-called Bali Nine heroin trafficking group, are among seven foreigners on death row for drug offences whose appeals for mercy have been rejected.

Indonesian authorities have confirmed the Australians will be among the next group to be executed.

Jakarta is remaining tight-lipped about who will join them or when. But it invited embassy officials from six nations -- Australia, France, Brazil, the Philippines, Nigeria and Ghana -- to a briefing Monday about how the executions will be carried out.

Atorney-general's office spokesman Tony Spontana confirmed that Chan and Sukumaran would be transferred this week from jail in Bali to Nusakambangan island, off the main island of Java and home to a high-security prison.

"They will be the first convicts who will be transferred, followed by the others," Spontana told AFP. "When everyone has been gathered, then we can carry out the executions."

When asked whether the other prisoners would be transferred this week to Nusakambangan, where six drug convicts were executed last month, Spontana replied: "Hopefully".

Australia's Sydney Morning Herald newspaper reported that the six judges who handed down the death penalties on Chan and Sukumaran were accused by the pair's lawyers of offering lighter sentences in exchange for money.

It said the allegation was made in a letter from the lawyers to Indonesia's Judicial Commission claiming a breach of ethics.

The lawyers added that the judges had come under pressure from "certain parties" to pass death sentences, the daily said.

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They have asked the Judicial Commission to investigate the bribe allegations, in yet another legal bid to postpone the executions.

But Judicial Commission chief Eman Suparman told AFP that without evidence and witnesses the challenge was unlikely to succeed, and even then it would have to go to a higher court.

"The Judicial Commission cannot change the decision," Suparman told AFP. "Only the Supreme Court is able to do so."

Spontana insisted the executions would go ahead, saying the legal process was completed and questioning why the bribe allegations were not aired at Chan and Sukumaran's final appeal.

Both the Australians and the other five foreigners on death row have lost their appeals for presidential clemency, their final hope of avoiding the firing squad.

There are other foreigners on death row in Indonesia whose cases are still pending.

Abbott earlier Monday vowed to pursue all legal options to save Chan and Sukumaran, promising everything possible was being done but not wanting to "peddle false hope".

"We'll be trying to ensure that all legal options are exhausted before something dreadful, final and irrevocable takes place," he told reporters.

But such appeals appear to have fallen on deaf ears. Indonesia's new president Joko Widodo has been a vocal supporter of capital punishment for drug offenders, disappointing rights activists who had hoped he would take a softer line.

Widodo has pledged not to grant clemency to drug traffickers while his country is in the grip of a "drug emergency", but many analysts speculate his tough stance could be an attempt to look decisive before his critics at home.