Foreign Minister Julie Bishop says the execution of the Bali nine ringleaders would be a grave injustice.

An emotional Ms Bishop made a speech in parliament on Thursday to plead for the lives of Andrew Chan and Myuran Sukumaran, who are expected to be executed in Indonesia within weeks.

Australia was not seeking to understate the gravity of their crimes, but the death penalty was a bridge too far, she said.

"This motion goes to the heart of what we believe will be a grave injustice against two Australian citizens facing execution in Indonesia," she told the lower house.

"Without doubt, Andrew and Myuran need to pay for their crimes with lengthy jail sentences but they should not need to pay with their lives."

Ms Bishop said more than 30,000 Australians have implored the Indonesian president and members of the Indonesian government for a stay of their executions.

Her shared hope with those petitioners was for the Indonesian government to show mercy, she said.

"I believe it is Indonesia that will lose the most from executing these two young men," she said.

No country had done as much as Australia to support Indonesia in fighting drug-related crime, Ms Bishop said.

Opposition foreign affairs spokeswoman Tanya Plibersek said capital punishment "barbarised" the executioner.

"It's left over from an earlier and more barbaric time," she said.

She said she remained hopeful the Indonesian government would show clemency and order a stay of execution.