Explosions rocked four churches in Indonesia's volatile Central Sulawesi province today and a man died in a separate blast in Jakarta.
The attacks shattered what had been relative calm during recent religious festivals.
A police spokesman said a grenade was either thrown at or exploded in the hands of a man standing outside a restaurant in Jakarta a couple of hours before dawn, killing him.
Police in the Central Sulawesi capital of Palu in the country's east said four blasts outside churches in the city - three hit simultaneously as the New Year began - wounded at least one policeman. The province has witnessed savage clashes between Muslims and Christians in the past three years.
The spokesman said he did not believe the explosions in Sulawesi and the national capital Jakarta were related. They occurred despite the presence of tens of thousands of police and soldiers on patrol to keep New Year's Eve celebrations in check that elsewhere went off without any trouble.
Some 200 people were in one of the churches when the midnight blasts hit, a local priest said. No worshippers were hurt.