"It's about 6.30pm here, which means it's 10.30am in Geneva, and if Australia's dozy diplomats can lodge their petition now, then it may have some effect," Mr Robertson said. Human rights lawyer Geoffrey Robertson, QC, speaks at a candlelit vigil for Andrew Chan and Myuran Sukumaran at Martin Place. Credit:Brendon Thorne "That's something we can do, something that will create - possibly - sufficient embarrassment for Indonesia to stay its hand." He said the executions of Chan and Sukumaran would breach international law in three ways: Because capital punishment should be kept to the worst offences, such as murder and terrorism, not drug smuggling

Because no execution should proceed while legal procedures are underway (i.e the Constitutional Court appeal due to be heard on May 12)

Because people should not be executed after a prolonged stay on death row, because "the constant alternation of hope with despair [amounts] to mental torture, and [is] contrary to the convention on torture"

Mr Robertson said Australia should also signify an intention to redirect aid from Indonesia to Nepal, establish an inquiry into the Indonesian attorney-general for "unlawful complicity in the deaths of these two Australians", and cease collaborating with Indonesian drug authorities until Indonesia stops executing drug smugglers of any nationality. "It's unconscionable to provide information that will send people to the firing squad," he said. Mr Robertson said that while he did not doubt the sincerity of Prime Minister Tony Abbott and Foreign Affairs Minister Julie Bishop's attempts to save Chan and Sukumaran, they could and should do more to warn Indonesia of the consequences. The human rights barrister has defended many international death penalty cases, including in the Privy Council, the highest court of appeal for many Commonwealth nations. He described the planned executions by firing squad as "operatic barbarism". "They will be offered a last cigarette, they will have a target pinned to their chest, they will be shot by a platoon of soldiers, several of whom will be issued with blanks for the pathetic pretence that they're not all responsible for the death," he said.

"Then, because death by firing squad does not often cause immediate loss of consciousness, they will have the coup de grace - a revolver at their head." The eleventh hour vigil was organised by the Mercy Campaign. It was not the first vigil asking Indonesia to halt the executions of Chan and Sukumaran, due to proceed in the early hours of Wednesday, but it was the most sombre. Many of the crowd bore signs begging the Indonesian president, Joko Widodo, to intervene and stop the executions. One sign declared: "God is merciful." Mercy Campaign organiser Brigid Delaney began by naming the seven other death row inmates scheduled to be put to death. "We stand with you," she said.

She said Chan and Sukumaran were inspiring people, "and I hope that whatever happens tonight they are never, ever forgotten".