Updated

At least 200,000 conservative Muslims rallied peacefully in the Indonesian capital on Friday in the second major protest against its minority Christian governor, who is being prosecuted for alleged blasphemy.

President Joko "Jokowi" Widodo, a political ally of the governor who angered hard-liners by being out of the city during their first protest, unexpectedly went to the national monument to join Friday prayers with the sprawling crowd. He called for protesters to leave peacefully. They cheered and then broke into chants calling for Gov. Basuki "Ahok" Tjahaja's arrest, but later, people streamed peacefully out of the area and marched to a major traffic circle before dispersing.

The blasphemy controversy erupted in September when a video circulated online of Ahok criticizing detractors who argued the Quran prohibits Muslims from having a non-Muslim leader.

It has challenged the image of Indonesia, the world's most populous Muslim nation that practices a moderate form of Islam, and has shaken the government of Jokowi, who accused unnamed political actors of trying to undermine him. The son of former President Susilo Bambang Yudhoyono is vying against Ahok for Jakarta governor in elections set for February.

Police said Friday they arrested eight people suspected of treason amid speculation they were plotting to undermine or topple Jokowi.

They included Rachmawati, the daughter of Indonesia's founding President Sukarno and the younger sister of former President Megawati Sukarnoiputri; retired army Gen. Kivlan Zein; and a well-known musician turned politician Ahmad Dani. Two other people were arrested for alleged crimes under Indonesia's law on electronic information and transactions.

Organizers had agreed to concentrate Friday's protest around the vaulting monument to reduce disruptions, but the area quickly overflowed. National Police spokesman Rikwanto, who goes by one name, estimated 200,000 people were on the streets. Police put on standby 22,000 officers and 5,000 soldiers.

A Nov. 4 protest against Ahok, the first ethnic Chinese to be Jakarta governor and the first Christian in half a century, attracted about 100,000 people. After nightfall, it turned violent, with one death and dozens injured. Police wanted Friday's protest to disperse in the early afternoon following prayers.

Lisnawati Djohar, a resident of West Sumatra's Padang city, said she flew to Jakarta with a dozen friends for the protest.

"I've been called to defend Islam," she said. "As a Muslim, I feel guilty if I refuse a demand to defend my religion. I believe Ahok insulted the holy Quran and it's hurt us."

Rizieq Syihab, leader of the Islamic Defenders Front, a vigilante group that helped organize the demonstrations, gave a fiery speech to the protest in which he asserted Indonesia would be peaceful if there was no blasphemy and other problems such as gays.

Speaking on the main stage at the national monument, National Police chief Gen. Tito Karnavian called for the protesters to support the legal process in the blasphemy case.

The accusation of blasphemy has animated the political opponents of Ahok and Jokowi, including hard-liners who have used the issue to seize a national stage for their extreme agenda, which includes the imposition of Shariah law in a secular nation.

Ahok's blasphemy case took a step forward Thursday when it was formally accepted for trial. The offense is punishable by up to five years in prison.

Police say Ahok can't leave the country during the case. However, hard-line Muslim groups continue to demand his arrest.

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Follow Wright at twitter.com/stephenwrightAP and Karmini at twitter.com/Niniek_AP