Indonesia's political and religious leaders are calling for calm ahead of a Friday protest by hardline Muslim groups, which are demanding Jakarta's governor be jailed over comments about the Koran.
A Christian and ethnic Chinese Indonesian, Governor Basuki Tjahaja Purnama, commonly referred to as Ahok, has long drawn the ire of hardline Muslim groups.
Ahok succeeded President Joko Widodo when he became the country's leader in 2014 and is now locked in an election battle with Agus Yudhoyono - the son of former Indonesian president Susilo Bambang Yudhoyono - and former education minister Anies Baswedan to retain his position.
Hardline religious groups have seized on verse Al Maidah 51 from the Koran, arguing Muslims should not allow themselves to be led by a Christian or a Jew.
When Ahok referred to this verse in a speech in late September, saying it was being used to lie to voters ahead of next year's elections, tensions were inflamed further.
Despite issuing an apology and insisting he was not insulting the Koran, the popular governor is currently under investigation for committing blasphemy.
Calling for a "constitutional jihad", the hardline group Islamic Defenders Front (FPI) are spearheading a rally in Jakarta on Friday, urging that police jail Ahok.
Police said organisers are expecting up to 50,000 people and that they will deploy about 18,000 officers and military personnel in response.
"We're afraid there will be some irresponsible people disturbing the rally," National Police Spokesman Agus Rianto told AAP.
Officers have been ordered not to carry firearms to ensure no shootings occur if the situation spirals out of control.
Fears of the protest turning violent prompted President Widodo on Monday to visit the home of his former rival in the 2014 presidential election, Prabowo Subianto.
President Widodo turned up on a white horse, donning a cowboy hat, and both called for calm and unity.
On Tuesday he met with the leaders of three of the largest Muslim organisations in the country.
Chairman of Nahdlatul Ulama Aqil Siroj said his members were forbidden from joining the protest and that Ahok's comments were simply a "slip of the tongue".
Director of the Institute for Policy Analysis of Conflict, Sidney Jones, said the government has repeatedly failed to confront hardline groups.
"This is why extremism and intolerance are growing in Indonesia: because no one dares draw a line and recognise religiously-inspired incitement for what it is, let alone condemn it or take measures to stop it," she wrote in a piece for the Lowy Institute's Interpreter about the upcoming protest.
But Professor Ikrar Nusa Bhakti from the Research Centre for Politics said a "soft approach" was the best way forward.
He said the FPI represented a fringe element, with protesters often gathered in buses from poorer areas outside Jakarta, fed lunch and given 50,000 rupiah ($A5) to attend.
Given Indonesia's history of political oppression it was important that people be allowed to express their views, as long as it is done peacefully, he added.
The Australian government issued a travel warning about the protest on Wednesday night saying demonstrations might take place in other cities.
While the overall level of advice has not altered, they said "avoid all protests and rallies as they can turn violent with little notice".
