Indonesian police on Friday arrested five Muslim activists ahead of a rally against the Christian governor of Jakarta, accusing them of plotting to overthrow the government.
One of those arrested was Muhammad Al Khaththath, the leader of the Islamic Community Forum, which spearheaded the planned rally demanding Jakarta Governor Basuki Tjahaja Purnama be sent to prison for alleged blasphemy linked to remarks deemed insulting to Islam.
"They were arrested on suspicions of a conspiracy to commit treason," said Jakarta police spokesman Prabowo Argo Yuwono.
Several thousand Muslims marched on Jakarta's streets after Friday prayers to demand that Purnama be detained and to call for a Muslim governor.
Riot police blocked the protesters from marching further to the presidential palace but allowed them to gather at a roundabout near the National Monument.
Al Khaththath's group is one of several Muslim organizations that backed massive street rallies in recent months demanding Purnama's prosecution.
Purnama, a key ally of President Joko Widodo and the first Christian to lead the capital in 50 years, is on trial in the blasphemy case. He also won the first round of the gubernatorial election on February 15.
He faces former education minister Anies Baswedan, a Muslim, in a run-off vote scheduled for April 19.
Indonesia is the world's most populous Muslim-majority country, but Christians make up about 10 per cent of the country's 250 million people.