Indonesia yesterday rejected an extraordinary last-ditch offer by Australia to exchange three Indonesian criminals in return for Jakarta sparing the lives of two Australian drug smugglers facing imminent execution.
The deal - believed to be the first of its kind in Australian history - came as the executions threatened to damage relations.
President Joko Widodo confirmed the offer of a swop had been rejected, insisting on "the sovereignty of the law" in Indonesia, Agence France-Presse said.
In an interview with Al Jazeera, Mr Joko said the men would be executed soon, but not this week.
Legal experts in Australia said they were not aware of any precedent for the offer, which most closely resembled prisoner- of-war exchanges under the Geneva Conventions.
An Australian expert on international law, Professor Don Rothwell, from the Australian National University, said he was not aware of previous swops.
"The fact that this proposal is even countenanced highlights the extraordinary diplomatic efforts the government is going through to find a breakthrough," he told The Straits Times.
Canberra last night signalled it would protest to Jakarta over the heavy-handed transfer of the prisoners, Andrew Chan and Myuran Sukumaran, and the emergence of photographs of a police commissioner posing with the men.
The commissioner told reporters he was trying to raise the spirits of the Australians and had no idea the photographs were being taken.
The prisoner swop proposal was made during a tense phone call on Tuesday night between Australian Foreign Minister Julie Bishop and her Indonesian counterpart, Mrs Retno Marsudi.
Ms Bishop apparently proposed to repatriate three Indonesian drug criminals in exchange for saving Chan and Sukumaran from the firing squad.
The Indonesians were reportedly the trio behind an attempt in 1998 to import 252kg of pure heroin aboard a boat that landed on Australia's east coast.
The men, Kristito Mandagi, Saud Siregar and Ismunandar, were the captain, the chief officer and the engineer of the boat. They pleaded not guilty but were convicted and received sentences of 20 years to life in prison.
Ms Bishop would not comment on the details of the proposal.
"What we are seeking to do is have an opportunity to talk about options that might be available in the area of prisoner transfer, a prisoner swop," Ms Bishop said.
Indonesia's Attorney-General Muhammad Prasetyo insisted that the executions would go ahead and that the offer from Australia was "not relevant", Agence France-Presse reported.
"Are you willing for people who have poisoned our nation to be exchanged?" he said. "That has never been carried out, and never thought of."
Chan and Sukumaran were arrested in 2005 after being caught using seven couriers to try to smuggle more than 8kg of heroin from Bali to Australia.
Thousands of people have participated in protests in Australia against the planned executions and Prime Minister Tony Abbott, the opposition leader and numerous ministers - including Ms Bishop - held a candlelight vigil outside Parliament in Canberra yesterday.
"We honour the friendship that we have with Indonesia, but we stand up for our values and we stand up for our citizens," Mr Abbott said.