Asia's main coffee exporters saw thin trading as demand fell ahead of Christmas break, while harvesting in Vietnam was going good on favourable weather, traders said on Thursday.

Harvest in Vietnam's coffee belt Central Highlands was 80-85 percent completed as steady sunshine helped the drying process, but low prices have discouraged some farmers from selling beans, traders said.

In Vietnam's major coffee-growing province Daklak, farmers quoted coffee beans at 36,500-37,000 dong per kg, little changed from last week's range 36,000-37,000 dong, tracking London prices.

The London ICE March robusta coffee settled flat at $1,713 a tonne on Wednesday. "Due to low prices, some farmers did not want to immediately pick beans from coffee trees. But this would lead to a larger proportion of ripe beans in harvest, ensuring high cup quality," said independent analyst Nguyen Quang Binh.

Traders quoted the 5-percent black and broken grade 2 robusta at a discount of $50-$70 per tonne to the ICE March futures contract, compared with a discount of $50-$75 per tonne a week earlier.

Delivery of coffee beans from the Central Highlands had been slow as farmers could not hire enough transport, said another trader, based in Ho Chi Minh City.

"Delivery slowed to 400-500 tonnes a day from around 1,000 tonnes before," he added.

A trader in Lampung said that in Indonesia, robusta coffee was traded with a $150 premium to the March contract.

Trading activities remained light as the market heads to holidays, but there were some transactions for March contract on Thursday, the trader said

Coffee harvest in some areas of Indonesia's Sumatra island usually falls around April.