Australia on Thursday suggested a prisoner swap with Indonesia in an 11th hour bid to save two drug smugglers facing execution, while voicing "deep concern" about Jakarta's international reputation if they are killed.

Andrew Chan and Myuran Sukumaran, the ringleaders of the so-called "Bali Nine" drug trafficking gang, could be shot within days after being moved on Wednesday to the Indonesian island where they are due to face a firing squad.

Authorities must give convicts 72 hours' notice before they are executed and in a last-ditch effort to save them Foreign Minister Julie Bishop proposed a prisoner swap.

She said she had spoken to her counterpart Retno Marsudi in what was reportedly "a very tense phone call".

"I've spoken to her on a number of occasions about this, and I wanted to explore any other avenues or opportunities to save the lives of these two young men who have been so remarkably rehabilitated," Bishop told ABC radio.

"She undertook to pass on my comments to the president.

"I didn't go into any specific detail but I did note there were Australian prisoners in Jakarta and there were Indonesian prisoners in Australia and that we should explore some opportunity, a prison swap, a transfer, whether that could be done under Indonesian law."

The Sydney Morning Herald reported that any deal could involve three Indonesians in prison in Australia over their role in an infamous 1998 drug bust.

They were named as Kristito Mandagi, Saud Siregar and Ismunandar, the captain, chief officer and engineer respectively of a boat carrying 390 kilograms (860 pounds) of heroin that was seized near Port Macquarie, some 400 kilometres (250 miles) north of Sydney.


Global implications

Bishop's comments followed an impromptu bipartisan candlelight vigil for the pair outside the country's parliament in Canberra early Thursday, also attended by Prime Minister Tony Abbott and opposition Labor leader Bill Shorten.

Abbott, who on Wednesday expressed revulsion at the looming deaths, said he had requested a final telephone call with Indonesian President Joko Widodo to again push for the men to be spared.

"I can't guarantee that request will be met," he said.

"We respect Indonesia and we honour the friendship that we have with Indonesia, but we stand up for our values and we stand up for our citizens, and these are Australian citizens in extremis."

Canberra has made more than 20 representations to Indonesian officials since January regarding the pair but Widodo has been unswayed, insisting Indonesia was facing an "emergency" due to rising narcotics use and a tough line must be taken.

Bishop warned Chan and Sukumaran's execution would have implications, not just in Australia but more globally.

"Of course, I'm deeply concerned about the impact of these executions not just on the Australian relationship with Indonesia but on Indonesia's reputation worldwide," she said.

"The movement against the death penalty is very strong.

"The sense of injustice of state-sponsored killings is very real, and we have been sending a message to Indonesia that its international standing will be damaged if it continues to execute successive numbers of citizens."

Chan and Sukumaran, sentenced to death in 2006 for trying to smuggle heroin out of Indonesia, recently lost their appeals for presidential clemency, typically the last chance to avoid the firing squad.

They are among several drug convicts, including foreigners from France, Brazil, the Philippines, Ghana and Nigeria, who have lost their clemency requests and are expected to be put to death at the same time soon.

Along with Australia, Brazil and France have also ramped up pressure on Jakarta, with Paris summoning Indonesia's envoy and the Brazilian president refusing to accept the credentials of the new Indonesian ambassador.