JAKARTA (Reuters) - More than 100,000 Indonesians are expected to rally on Friday to call for the arrest of the Christian governor of the capital, Jakarta, for alleged blasphemy, as police staged drills and prepared water cannon after violence at a protest last month.

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Authorities are hoping to avoid a repeat of Nov. 4 when one person killed and more than 100 wounded in clashes with police during a similar rally led by hardline Islamists.

Muslim groups accuse Governor Basuki Tjahaja Purnama of insulting the Koran, though they have pledged that Friday’s demonstration will be peaceful.[nL4N1DT2W6].

Police brought in water cannon and barbed wire to the site of the rally, a central Jakarta park, on Thursday.

“We are expecting over 100,000 participants,” said Jakarta police spokesman Argo Yuwono.

“There is enough security so the public need not worry. We hope everything will proceed according to the agreement with the protesters.”

Indonesia has the world’s biggest Muslim population but recognizes six religions and is home to dozens of ethnic groups, some of which follow traditional beliefs.

Purnama, an ethnic Chinese Christian, is being investigated over comments he made about his opponents’ use of the Koran in political campaigning. He has denied wrongdoing but apologized for the remarks.

Police on Thursday handed over their investigation dossier to prosecutors, who are expected to take the case to court in coming weeks.

Simmering religious and ethnic tension have prompted President Joko Widodo to rally top military, political, and religious figures in a sign of unity amid fears of attempts to undermine the stability of his government. [nL4N1DN1MJ]

Police helicopters last week dropped leaflets over the capital warning residents of harsh penalties if the upcoming rally turned violent. [nL4N1DO2DO]

Tens of thousands participated in military-led rallies in several cities this week calling for unity and celebrating Indonesia’s diversity.

The Jakarta government has also put up billboards on major roads calling for national unity and displaying pictures of independence heroes who fought against colonial rule.

The Australian foreign ministry and the U.S. embassy in Jakarta issued security notices urging nationals to avoid the demonstration.

Purnama, popularly known as Ahok, is running for re-election in February against two Muslim candidates. The governor who is popular with many for pushing through tough reforms to clean up the teeming city, has slipped into second place in the race, opinion polls showed this week.