The men -- the last behind bars among nine Australian smugglers who were jailed in Indonesia in 2005 -- flew into Darwin on Sunday under a secretive deal between the two countries.

"The five men are relieved and happy to be back in Australia," said a statement released on behalf of the men, their families and their lawyers.

"They look forward, in time, to reintegrating back into and contributing to society," said the statement received Monday.

The National Police arrested the nine Australians in 2005, convicting them of attempting to smuggle more than eight kilograms (18 pounds) of heroin off Bali.

The case drew global attention to Indonesia's unforgiving drug laws, with two of the gang executed by firing squad, while the others served hefty prison sentences.

The released men -- Matthew Norman, Scott Rush, Martin Stephens, Si Yi Chen, and Michael Czugaj -- said they were "immensely grateful" to President Prabowo Subianto for allowing them to return home.

Support from friends, family, lawyers and government officials had been "essential and invaluable", they said.

The men now need "time and support" for their welfare, the statement said, asking media and the community to make allowance for this.

Australia has not released details of the agreement with Indonesia that allowed their release.

Australian public broadcaster ABC said the men did not have to serve further prison time but had agreed voluntarily to continue their rehabilitation.

Prime Minister Anthony Albanese said Sunday he had thanked President Prabowo for his "compassion" in allowing the men's return.

"These Australians spent more than 19 years in prison in Indonesia. It was time for them to come home," he said.

"We would like to convey our deep appreciation to the Government of Indonesia for its cooperation to facilitate the men's return to Australia on humanitarian grounds," Albanese said.

It said the men's return reflected "the strong bilateral relationship and mutual respect between Indonesia and Australia."

"The men will have the opportunity to continue their personal rehabilitation and reintegration in Australia."

Indonesia has some of the world's toughest drug laws, including the death penalty for traffickers.

Accused "Bali Nine" ringleaders Andrew Chan and Myuran Sukumaran were executed by firing squad in 2015 despite repeated pleas from the Australian government, which recalled its ambassador at the time.

Tan Duc Thanh Nguyen died of cancer in 2018, months before Renae Lawrence was released after her sentence was commuted.