Indonesia's Attorney-General and chief advocate for executing drug felons, H.M. Prasetyo, was a senior figure in the office of the Attorney-General in 2006 when it allegedly intervened to insist the Bali nine duo get the death penalty.

Fairfax Media revealed on Monday claims by the former lawyer for the Bali nine pair, Muhammad Rifan, that he was asked to pay 1 billion rupiah, about $130,000 at the time, to judges to ensure Andrew Chan and Myuran Sukumaran got a sentence of less than 20 years in prison.

The deal collapsed, he says, after the Attorney-General's office and the Supreme Court intervened and told the judges to impose the death penalty.

The judges, from the Denpasar District Court, responded to the edict from Jakarta by asking for a "lot more money" to hand down a lighter sentence, Mr Rifan alleges. He was unable to pay the money and the death sentence was given.

Mr Prasetyo was deputy attorney-general at the time, a senior bureaucratic position. He left later that year to embark on a political career as a member of Partai Nasional Demokrat.

He was appointed to cabinet as Attorney-General by Indonesian President Joko Widodo last year, a controversial move because the position - crucial to combating Indonesia's endemic corruption - is seen as better done by an individual with no political affiliations.

Ever since his appointment, Mr Prasetyo has led the push for the executions of Chan and Sukumaran and other drug convicts, repeatedly saying their various legal appeals will fail.

Nine drug felons, including the two Australians, are due to be executed at midnight on Tuesday, or shortly after.

Mr Prasetyo has also said that the executions should take place before Indonesia's judicial commission - which examines claims of judicial wrongdoing - completes its investigation into the claims. He says the investigation is irrelevant.

Mr Prasetyo could not be reached for comment on Monday.

Fairfax Media is not suggesting he knew about the alleged negotiations for money nor was involved in the alleged intervention from Jakarta.

But as the most senior deputy attorney-general at the time, in charge of general crimes and the examination of legal actions, there is a clear potential for a conflict of interest.

Mr Rifan has vowed to provide further details of the alleged corruption to the judicial commission, if they ever get around to contacting him despite starting their probe almost two months ago.

Australia's Minister for Foreign Affairs Julie Bishop said Mr Rifan's allegations were "very serious".

"They call into question the integrity of the sentencing process," she said. "[It] underlines why we continue to request Indonesia to allow the judicial commission to finalise its review ... An execution is an irrevocable step and I believe that these hearings and these appeal processes should be concluded before any decision is taken."

Meanwhile, lawyers for Chan and Sukumaran echoed Ms Bishop's concerns about the "disturbing" allegations.

"This is unfair," Indonesian human rights lawyer Todung Mulya Lubis told reporters. "People should not be executed if the judgment came from a defective process.

"We appeal to the Attorney-General. We appeal to the President. In the name of due process of law, fairness and justice, do not do the executions."

But, as United Nations secretary Ban Ki-moon urged the executions to be halted in a new statement, Ms Bishop said she was yet to see any evidence that the ratcheting up of international pressure on Indonesia was having an impact.