JAKARTA (Reuters) - Indonesian President Joko Widodo said on Tuesday he was determined to “prevent the growth of radicalism”, after reports that Islamist extremists are planning protests to destabilize his government.

A man touches a large Indonesian flag as he takes part in a rally against what organizers see as growing racial and religious intolerance in the world's largest Muslim-majority country, in Jakarta, Indonesia. REUTERS/Iqro Rinaldi

Officials say there has been mounting alarm in the government since more than 100,000 Muslims, led by hardline Islamists, took to the streets of Jakarta on Nov. 4 to demand the removal of the capital’s governor, a Christian, for alleged blasphemy.

National Police Chief Tito Karnavian warned on Monday of a threat to parliament during rallies expected this Friday and on Dec. 2.

“There are hidden methods by certain groups to enter and occupy parliament,” Indonesian media quoted him as saying.

“If (these actions) are intended to overthrow the government, that’s a violation of the law.”

Widodo has blamed “political actors” for fanning violence during the Nov. 4 protest, without naming anyone.

The president held talks with a senior coalition partner on Tuesday, the latest in a series of meetings with top political, religious and military officials to signal the unity of his government and support from the security establishment.

“I want to emphasize the spirit of pluralism,” he told reporters after the meeting at the presidential palace.

“The government is determined to prevent the growth of radicalism in this country.”

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Widodo, the leader of his party Megawati Sukarnoputri and opposition leader Prabowo Subianto have all called for calm.

On Tuesday the president tried to assuage concerns among investors in Southeast Asia’s largest economy.

POLITICS “A LITTLE HEATED”

“The political situation has been a little heated recently, but this is very normal around elections,” he said in a speech, referring to upcoming local elections in Jakarta.

“There is no reason to be pessimistic,” he told the event attended by bankers, investors, and top company executives, adding that inflation and growth were both in line with government targets.

The trigger for the tensions was a comment that Jakarta governor Basuki Tjahaja Purnama, the first Christian and ethnic Chinese in the job, made about his opponents’ use of the Koran in political campaigning.

Purnama, popularly known as Ahok, is running for re-election in February against two Muslim candidates, including the son of former President Susilo Bambang Yudhoyono. Widodo has been seen as one of the governor’s main supporters.

Police have opened an investigation into the allegations that Purnama insulted the Koran and questioned him on Tuesday. Prosecutors are expected to bring a case to court in the coming weeks. He could face up to five years in prison if found guilty of blasphemy.

Police said they were investigating a social media campaign calling for a run on banks on Nov. 25 in protest over the government’s handling of the complaint against Purnama. Government officials have urged the public not to participate and played down the potential impact of any such campaign.

Indonesia has the world’s largest Muslim population and is also home to Christian and Hindu communities.