Australia has offered to pay for the cost of Bali Nine pair’s imprisonment if Indonesia would just spare their lives. Foreign Affairs Minister Julie Bishop wrote a letter to her Indonesian counterpart Retno Marsudi to offer another bargaining deal for Andrew Chan and Myuran Sukumaran.

“My dear Retno,” Bishop’s letter reads, as quoted by the Sydney Morning Herald. It apparently details Australia’s “one-off” offer to exchange three Indonesian prisoners in Australia for Chan and Sukumaran’s clemency. As an incentive, Australia will be covering the cost of the Bali Nine duo’s imprisonment in the Asian nation.

“The Australian government would be prepared to cover the costs of the ongoing life imprisonment of Mr Chan and Mr Sukumaran should a transfer not be possible,” Bishop wrote. “The vast majority of Australians very strongly support the government’s efforts to seek clemency for Mr Chan and Mr Sukumaran.”

The Australian minister added a warning, though, that Chan and Sukumaran’s execution might “compromise the strong tie we have worked so hard to foster over many years.”

The letter was sent two days after Bishop and Marsudi’s “very tense” phone conversation about the same. The Indonesian prisoners in question were Kristito Mandagi, Saud Siregar and Ismunandar, who were the captain, the chief officer and the engineer of an Australian-bound boat carrying 390 kg of heroin. The amount of the drugs found in them was 47 times the amount of heroin the Bali Nine gang planned to smuggle to Australia.

Marsudi formally rejected the prisoner swap offer three days later, saying there is no legal basis in Indonesian law that would allow such exchange. “The president is of the position that such an exchange cannot be undertaken,” she wrote on March 8.

However, Marsudi’s rejection letter did not address Australia’s offer to pay for the imprisonment costs of Chan and Sukumaran. The Bali Nine ringleaders’ Australian lawyer Peter Morrissey told Seven Network that the country’s offer is “attractive,” but he doubted if it’s attractive enough for Indonesian authorities.

“Whether that on its own will do the trick, I doubt,” he said. “I think Indonesia will consider the whole range of things that Julie Bishop and Tony Abbott have put forward.”

Chan and Sukumaran have already been transferred from Kerobokan prison to Nusakambangan Island for their execution. However, the exact date of which has not been revealed yet.