Australia called for an urgent investigation on 27 April into reports alleging two Australian drug traffickers were sentenced to death in an Indonesian trial tainted by corruption.

Foreign Minister Julie Bishop called on Indonesia to investigate the allegations before anyone is executed.

"These allegations are very serious. They call into question the integrity of the sentencing process and it's a matter for Indonesia's judicial commission to investigate these matters and that underlines why we continue to request Indonesia to allow the judicial commission to finalise its review. This must be allowed to continue before any action is taken to prepare for executions. An execution is an irrevocable step and I believe that these hearings and these appeal processes should be concluded before any decision is taken," Bishop told reporters in Sydney.

Indonesia's foreign ministry said Australia needed to show proof before an investigation can take place into the trial or sentencing of Bali Nine members Andrew Chan and Myuran Sukumaran.

Bali-based lawyer Muhammad Rifan told the Sydney Morning Herald that he had agreed to pay Chan and Sukumaran's judges more than A$130,000 (£67,000, $101,647) to give them a prison term of less than 20 years.

Rifan said the deal fell through when the judges told him they had been ordered by senior legal and government members in Jakarta to impose a death penalty and he didn't have enough money to meet a revised, higher demand for a lighter sentence.

"Again, I respectfully call on President Widodo to reconsider his refusal to grant clemency. It is not too late for a change of heart. We ask no more of Indonesia than Indonesia asks of other countries in relation to its nationals who are on death row in other countries, including for drug offences," Bishop said.

Indonesia said the two Australians on death row have been given all legal avenues to challenge their sentences. Bishop also expressed condolences for the victims of the Nepal earthquake and promised to continue assisting the aid and relief effort.

"On behalf of the Australian Government I express our deepest condolences to the government of Nepal and the families who have lost loved ones in the aftermath of the earthquake in Nepal, India and Bangladesh. We are deeply saddened by the images that are coming from Nepal and we will continue to work with Nepalese authorities in whatever way we can," she said.

"We have been able to confirm the safety of more than 850 Australians in the country. I do hold grave fears for the welfare of one Australian who was known to be at the Mount Everest base camp where a number of deaths have occurred. We are currently working to confirm this person's identity," she said.

A total of 3,218 people were confirmed killed in Saturday's 7.9 magnitude quake, the worst in Nepal since 1934 when 8,500 died. More than 6,500 were injured.