Domestic robusta prices in Vietnam were steady this week on both thin supply and buying demand, with traders keeping close eyes on the weather and COVID-19 prevention policies ahead of the main harvest season next month.

Farmers in the Central Highlands, Vietnam's largest coffee-growing area, sold coffee at 39,400-41,800 dong ($1.73-$1.84) per kg, little changed from last week's 39,700-42,000 dong range.

"The weather has been favourable recently with a mix of rainy and sunny days, which is actually a boost to the coffee beans to ripe faster and better," said a trader based in Dak Lak province.

"But it's storm season now, if it rains next month, bean's quality will be severely hurt," the trader added.

Apart from weather condition, traders also are concerned that newly detected COVID-19 clusters in Dak Lak and neighbouring Gia Lai province may trigger travel restrictions and hinder cherry picking and trading activities amid new beans are due to come next month.

London ICE November futures settled up $11, or 1%, at $2,131 per tonne on Wednesday.

Traders in Vietnam offered 5% black and broken grade 2 robusta at a discount of $220 per tonne to the January contract, unchanged from a week ago.

In Indonesia's Lampung province, traders offered Sumatran robusta beans with $210-$220 discounts to the November and December contracts and $250 discount to the January contract.

Last week, beans were offered at discounts ranging from $230-$250 to the January and February contracts.

Traders said Sumatran robusta bean prices this week were firmer as harvest had ended and many farmers were holding on their remaining stocks.