President Widodo, widely known as Jokowi, confirmed on Friday that Bashir would be released from prison next week – he could walk free as soon as Monday – even though the 81-year-old cleric has more than six years left to serve in jail for terrorism-related crimes.

The firebrand cleric will have no conditions placed on his release, according to Widodo's legal adviser Yusril Ihza Mahendra, which could open the door to him preaching an extreme form of Islam once again.

Prime Minister Scott Morrison said Australia had "the deepest of reservations" about Bashir's early release, while a spokesman for presidential candidate Prabowo Subianto suggested the release may have been announced to win Widodo voter support ahead of the April 17 election.

Bashir was the spiritual leader of terror group Jemaah Islamiyah, which committed the 2002 Bali bombings.

Those bombs killed 202 people, including 88 Australians, and Bashir was initially convicted of conspiracy over his role in the bombings – a conviction overturned after he had spent 26 months in prison.

In 2011, he was jailed for inciting terrorism and financing an Aceh-based terrorist cell; he has served nine years of that 15-year sentence.

Melbourne man Jan Laczynski, who lost five friends in the blasts, told The Age and The Sydney Morning Herald the President should have considered "all the people all around the world who are still suffering because of this bombing".

"Who is next? Ali Imron, the guy who made the bomb? It’s frightening," Mr Laczynski said.

"It’s a slap in the face for so many Australians who are still injured and still recovering.

"Widodo wants to give clemency, leniency; for goodness' sake, there are a lot of people in Australia still hurting right now."

Indonesian man Dewa Ketut Rudita, who suffered burns to 35 per cent of his body in the blasts and had his right eye injured, said he was "disappointed, of course".

"If humanitarian reasons are the reason given for his release, shouldn't it be asked where was his humanity when he committed the crime that took so many lives? [Many people are] suffering still, the survivors and families of the victims," he said.

"As a human with empathy, I understand that he is old, I empathise with that. But shouldn't the victims and families of the bombings be given consideration? How we would feel about it?"

Mr Morrison said on Saturday that Canberra had spoken to Jakarta about the early release of Bashir and that "Australia's position on this matter has not changed".

"We have always expressed the deepest of reservations and we will continue to work closely with Indonesia on this issue. We are partners when it comes to countering terrorism and religious extremism and we will continue to do that," he said.

Relations between Canberra and Jakarta have been strained in recent months since Mr Morrison revealed Australia would consider moving its embassy in Israel from Tel Aviv in Jerusalem, despite a subsequent partial backdown from that plan. The free-trade deal between the two nations has still not been signed.

Yusril Ihza Mahendra – who successfully lobbied Widodo for Bashir's early release – said the elderly cleric would be released unconditionally and the President had personally involved himself in the case in anticipation of concerns from friendly governments including Australia and the United States.

"Actually releasing a convict should be the role of the Minister of Law and Human Rights and all the agencies under him including the corrections agency. But the President took over the authority just in case there will be questions from other countries," he said.

Bashir's lawyer, Muhammad Mahendradatta, said on Saturday that the release was not extraordinary and that "this is a legal case, this is not a political issue. It has legal grounds".

"God willing, as promised by the President or Yusril, the plan is that [he will be released] next week. Next week can mean Monday, Tuesday, Wednesday or Thursday. How it will happen [what legal avenue will be taken to release him] it's not our authority, it's the government."

Asked if Bashir could return to preaching, Mahendradatta said "it's an unconditional release from both sides, from the government and Bashir".

Wednesday or Thursday is considered the most likely day for Bashir's release.

Dahnil Anzar Simanjuntak, the spokesman for the Prabowo campaign, told the Antara news agency that "apart from the political element, we are grateful that he was released for humanitarian reasons, moreover he is already old, because it is time".

Dahnil said it was unfortunate the Widodo government had only recently made efforts to liberate Bashir, noting the 2019 election campaign was now under way.

Sidney Jones, one of the world's leading counter-terrorism experts and the director of the Jakarta-based Institute of Policy Analysis of Conflict, said the timing of the release was "strange".

"If Jokowi didn’t want all the speculation about political motivations, why not wait a few months [until after the election] for the release?"

Jones said it would not be a "huge risk" to allow Bashir to return to his home town of Solo as he had reversed his support for Islamic State several years ago.

"He won’t be touring the country rabble-rousing as he has done in the past. But he is very much the elder statesman of the extremist movement, so there will be an endless flood of visitors to his house," she said.

The release of the elderly cleric did not signal, she said, diminished support from Indonesia for tackling extremism.