Indonesian police say they have found almost 30 bombs plus guns and ammunition in a district where Muslims and Christians have battled in recent years.

The bombs and weapons were found on cocoa plantations in the Poso district of Central Sulawesi on Monday, said Police Sergeant Major Pangeran.

He said 27 bombs, one rifle and a number of bullets were found at a plantation in Ratulene and two home-made handguns were found at Tabalu. An invesigation was under way to trace the owners.

Poso district police chief, Abdi Dharma, told the state Antara news agency he believed the bombs and weapons had been put there for the police to find.

He said some residents wanted to hand over weapons to police, who have been conducting a drive to disarm the district, but did not have the courage to do so.

Up to 1,000 people were killed in Muslim-Christian battles after sectarian violence broke out in Poso in 2000. The government brokered a shaky peace deal in December 2001 but sporadic violence continues.

In the worst bloodshed in 2003, gunmen in October killed 10 people in attacks on mainly Christian villages. A senior security official has blamed the al-Qaeda-linked Jemaah Islamiyah terror group for those killings.

A small bomb was discovered on a bridge in the district capital of Poso on Monday. A bomb blast marred New Year's eve in Poso but caused no casualties.