Domestic coffee prices in Vietnam edged higher this week on scarce supply, while trading activities in Indonesia remained sluggish, traders said on Thursday.

Farmers in the Central Highlands, Vietnam's largest coffee-growing area, sold coffee at 31,000-32,000 dong ($1.32-$1.37) per kg, compared to 29,500 dong two weeks ago.

"Not so many traders are buying at these prices as we can't make any profits, while farmers are reluctant to sell in anticipation of higher prices," said a trader based in the coffee belt. "Farmers have already sold at least 85% of their beans," he added.

Traders in Vietnam offered 5% black and broken grade 2 robusta at $200 premium per tonne to the July contract on Thursday, higher than the $150 premium of two weeks ago.

Another trader said buyers could turn to Indonesia for fresh beans which will come in bulk in June but the prices there would not likely be cheaper.

Traders in Vietnam offered 5% black and broken grade 2 robusta at $200 premium per tonne to the July contract on Thursday, higher than the $150 premium of two weeks ago.

July robusta coffee settled up $1 at $1,201 per tonne on Wednesday.

Indonesian robusta beans in Lampung province were offered with $260-$270 premium to July contract this week, according to a trader in Sumatra, narrowing from $300-$310 premium two weeks ago, as new supply of coffee started coming in.