Supporters of two Australian men facing death by firing squad in Indonesia say there's still hope for them.

Indonesia's president has turned down clemency pleas for the two men...who were part of the Bali Nine group of heroin smugglers.

They could be executed in the next few weeks.

And Australia's Prime Minister Tony Abbott says diplomatic channels are also working to save the mens' lives.

"We're redoubling our efforts, through what we hope might be effective channels, but this is not going to be easy I've got to say."