Coffee trading in Vietnam continued on a sluggish note this week as stockpiles dwindled, while a busy Indonesian market saw more produce from its main harvest, traders said on Thursday.

Farmers in the Central Highlands, Vietnam's largest coffee growing area, sold coffee at 35,000 dong ($1.51) per kg, unchanged from last week.

"Very few exports deals were struck in the last couple of weeks due to low supply at the end of the 2018/19 crop season," a Ho Chi Minh City-based trader said.

"Trading activities will stay muted until the next harvest that will begin in October," he added.

Another trader based in the Central Highlands said it was still too soon to forecast the output of the upcoming harvest, but the weather has been favourable for coffee trees.

Vietnam's coffee exports in the first seven months of this year fell 9.6% from a year earlier to about 1.06 million tonnes, official data shows.

Traders in Vietnam offered 5% black and broken grade 2 robusta at $220-$250 per tonne, premium to the November contract, compared with a range of $170-$180 premium a week ago.

November robusta coffee settled up $4, or 0.3%, at $1,328 per tonne on Wednesday.

Meanwhile, trading activity in Indonesia was busier this week, a trader said, with more supply coming in this week despite the harvest season coming to an end.

Sumatran robusta beans are offered with $150 premium this week to the November contract. That compared with $170-$220 premium last week, a trader in Indonesia's Lampung province said.

"We suspect farmers still have decent stock of beans and they are selling them little by little," the trader said.