The alleged mastermind of the Bali bombings will not be released from prison early unless he renounces radicalism, Indonesia's president has said - backtracking from plans to free him imminently without conditions.

Joko Widodo said radical cleric Abu Bakar Bashir must agree to pledge loyalty to the state to win his parole.

It follows a surprise announcement last Friday that the 80-year-old was being granted early release on humanitarian grounds as the preacher was "old and sick".

The plan immediately drew sharp criticism at home and abroad, with Australia's leader warning Bashir was still a threat.

The 2002 Bali bombings killed 202 people, including 88 Australians and 28 Britons.


Image: The 2002 Bali bombings killed 202 people

Australian Prime Minister Scott Morrison urged Indonesia's government to show respect to the victims.

"We don't want this character able to go out there and incite the killing of Australians and Indonesians, preaching a doctrine of hate," Mr Morrison said.

Following mounting opposition, Indonesia announced a review of the decision with its president later saying prisoners who wanted early release must fulfil certain criteria such as renouncing extremist ideology.

Bashir insists he is only answerable to God and that Indonesia should be governed by Islamic rather than civil law.

Image: Mr Widodo faced criticism for his decision to grant Bashir early release

"Abu Bakar Bashir is already old and his health is also deteriorating," Mr Widodo told reporters.

"You can imagine if we as children see our parents sick. However, we also have a legal system here.

"There are legal mechanisms that we must go through. This is parole, not pure release but conditional release, so the conditions must be fulfilled first."

The initial decision to permit Bashir's early release was announced during presidential election campaigning in which opponents of Mr Widodo tried to discredit him as insufficiently Islamic.

Abu Bakar Bashir was sentenced to 15 years in prison in 2011 for helping to fund a paramilitary group training in the conservative Islamic province of Aceh.

He has repeatedly denied involvement in the Bali terror attacks and a previous conviction was quashed on appeal.

Bashir's lawyer Achmad Michdan questioned the apparent official change of heart.

"We have no problem with (the review) but people might wonder why would they announce it in the first place," Mr Michdan told AFP.