Indonesian prosecutors have demanded up to seven years' jail for a self-described "commander" of radical Islamists who allegedly led a mob attack on a rally of religious moderates.

Hundreds of police, including crack paramilitary officers, formed a cordon outside the Central Jakarta District Court on Friday for the trial of Munarman over the attack in the capital in June.

Islamic Defenders Front militant Munarman was read charges of assault and inciting violence in a courtroom packed with white-clad supporters shouting "Allahu akbar" (God is great).

Rizieq Shihab, the leader of the group, was charged last week and faces five-and-a-half years jail over the attack, which saw scores of religious fanatics armed with wooden sticks set upon the peaceful rally at the city's national monument.

Several people were injured as the extremists beat unarmed demonstrators including old women and children in front of police, who failed to prevent the onslaught.

The Front, which wants sharia or Islamic law, has launched a series of vigilante attacks since 2000, with targets including the US embassy and nightclubs.

Militant behaviour and the government's moves to restrict the activities of the minority Ahmadiyah Islamic sect have raised concerns that religious freedom is under attack in the world's most populous Muslim country.