Indon ambassador defends Bali duo decision

Indonesia's ambassador Nadjib Riphat Kesoema has written to federal parliament defending his government's decision not to save two Australian drug smugglers on death row.

The Senate last month urged the Indonesian government to spare the lives of Bali Nine duo Andrew Chan and Myuran Sukumaran, who are expected to face the firing squad in the next few days.

In response, Mr Kesoema said the decision not to pardon the pair was very difficult for President Joko Widodo on both a personal and humanitarian level.

However, the drug problem had "blossomed into a national emergency" and required strong law enforcement.

"Most tragically, drugs and their traffickers and producers have denied too many people including children of their right to life," he wrote.

Mr Kesoema said both cases had been granted due process of law and all legal avenues had been pursued.

He defended the court's decision to impose the death penalty and said separation of powers meant the government could not meddle in judicial processes.

The upper house had argued the sentences should be commuted to a prison term due to the pair's genuine remorse and rehabilitation.

Chan and Sukumaran were transferred to Nusakambangan island on Wednesday to await their execution.