Jakarta – Indonesia's armed forces chief General Feisal Tanjung said on Friday the military would take sterner measures against riots following disturbances in a town east of Jakarta in which buildings were burned or wrecked.

"If riots continue, the armed forces will take sterner action ... because this country is based on the rule of law," the official Antara news agency quoted him as saying.

Troops patrolled the town of Rengasdengklok, about 50 kilometres east of Jakarta, and residents cleared rubble from wrecked buildings after a Muslim mob went on the rampage on Thursday over a reported insult against Islam, witnesses said.

Rioters burned a church and a Chinese Buddhist temple, wrecked four other churches, and destroyed and looted shops and homes during a rampage on Thursday, officials and residents said. Sixteen cars were also destroyed.

There were no reports of serious injuries.

The rupiah fell against the dollar on Friday morning but later recovered on a nervous money market on rumours of trouble in the major west Java city of Bandung.

Bandung residents said thousands of workers from a nearby textile factory were demonstrating in demand of a bonus. Police said two cars were set on fire but the situation was quickly brought under control.

Government officials said Thursday's riot in Rengasdengklok apparently started after an ethnic Chinese woman complained of the noise Muslim youths were making as they beat drums before dawn to summon people to eat before the start of the daylight Ramadan fast.

Residents said troops were stationed in many parts of the town, which is part of the Karawang regency, a rice-growing area east of Jakarta.

Last month, four people died when a mob went on a rampage in the town of Tasikmalaya in West Java, setting fire to shops, buildings and churches. That riot was sparked by reports of police brutality towards a Muslim religious teacher.

Political and social analysts have blamed the eruptions of violence on socio-economic tensions. Some government members have said they believed there was a Maoist conspiracy involved but have provided no proof of this.

While more than 80 per cent of Indonesia's nearly 200 million people are Muslims, the state recognises the world's major religions.