JAKARTA, Indonesia (AP) — 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 Purnama’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 tolerance associated with Islam in Indonesia, the world’s most populous Muslim nation, 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. National Police spokesman Boy Rafli Amar told reporters the group planned to use the protest to incite chaos and overthrow the government.

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.