Chan and Sukumaran were formally given 72 hours notifice of their executions on Saturday, prompting Foreign Minister Julie Bishop to call on Indonesian President Joko Widodo to reconsider his refusal to grant clemency.

Ms Bishop's Labor counterpart, Tanya Plibersek, said on Sunday morning that

"Both Mr Chan and Mr Sukumaran know they committed a very serious crime. They have demonstrated genuine remorse, but know they must pay a heavy price," she said.

"Labor pleads with the Indonesian Government to show them mercy. It's not too late. We continue to offer the Australian Government every support for its efforts to secure clemency for Mr Chan and Mr Sukumaran. While there's life, there's hope."

And Greens leader Christine Milne called on Prime Minister Tony Abbott to try and stop the executions.

"I think it has come down to the last minute and I would encourage the prime minister to intervene at the highest level," she told Sky News.

"I would like to appeal to the Indonesians to extend clemency."

Senator Milne said that, at the very least, the government should be doing everything it could to delay the executions.

Lawyers for the Australians are challenging Indonesia's clemency laws in the Constitutional Court but