At least 10 people have been killed in Indonesia after violence flared between Muslims and Christians in the province of Maluku. Maluku is known for religious tension, but had been significantly more peaceful in recent months.

The violence flared when a small, mainly Christian separatist movement tried to raise an independence flag Sunday on the streets of the city of Ambon. The street battles have raised fears of a new outbreak of the sectarian battles that killed more than 9,000 people between 1999 and 2002.

In Sunday's unrest, three buildings, including a church and a United Nations office, were burned down.

Local and international agencies have done substantial work to reduce tensions between the Christian and Muslim communities in Ambon. Until Sunday, their efforts had seemed to be on the road to success.

"This is a great pity because there really had been big reconciliation efforts going on both from the government, from NGO's, from religious leaders," says Patrick Sweeting, head of the United Nations Development Program's Crisis Prevention and Recovery Unit in Indonesia. "So this could potentially set things back. Let's wait and see whether or not this is a flash in the pan or something that is going to be symptomatic, but obviously it is going to unsettle a lot of people."

Much of the infrastructure destroyed in fighting a few years ago had been rebuilt, including the church that burned down Sunday. It had been awaiting a formal reopening ceremony.

Indonesia is the world's largest Muslim country, but there is a substantial Christian minority. In general there is little tension between the two faiths, but in some areas - such as Maluku and central Sulawesi, religious militants have been stirring trouble.

The government has clamped down on militant groups, believing them to be a breeding ground for terrorists. There was a heavy security presence on the streets of Ambon Monday to forestall further clashes, but sporadic gunfire was heard overnight, and buildings were still burning Monday morning.