But more than 200 people have been killed since May in a wave of violence in Aceh involving armed rebels and Indonesian troops.

The workers on the plantations were often settlers from the main island of Java, who have become a target of repeated attacks amid escalating violence. They have largely fled.

``The main issue is security. Buyers are reluctant to take positions while farmers are worried about their safety because plantations are located in remote highlands,'' said one trader in Medan, North Sumatra.

``I think 30 per cent of the arabica plantations in Aceh have been abandoned. You may not hear fresh violence lately, but still everyone is cautious,'' said the trader who has a plantation in Aceh.

Many coffee players who trade in Aceh's arabica are based in Medan, a key commodity trading city in Sumatra which is also the main export port for coffee from Aceh.

Coffee is transported by land from Aceh to Medan, but the main road linking the two provinces has often been disrupted by violence. Road transport firms suspended operations on a number of occasions after a spate of arson attacks.

``Harvesting has started in Aceh, but they just cannot find workers to harvest the coffee. Workers used to be the Javanese settlers, but they have gone because of the violence,'' said another trader in Medan.

Indonesia's arabica output constitutes up to 15 per cent of the country's coffee production, which is expected to stand at 450,000 tonnes in 1999-00 (Oct-Sept) against 380,000 tonnes in 1998-99.

Traders said they had yet to estimate a decline in output because of the unattended coffee farms. The official Antara news agency said on Thursday that Aceh exported 3,688 tonnes of arabica in Jan-Sept against 4,011 tonnes at the same period in 1998.

It said the coffee was exported to the United States, Japan, Taiwan, Singapore, Germany and Denmark. Dry-processed arabica is currently on sale at 14,000-15,000 rupiah/kg.