HANOI: Vietnam coffee export prices slid to discounts against the international benchmark, as robusta prices in London rose last week on supply worries, while Indonesia’s Sumatran robusta premiums tumbled on rising supplies, traders said.

Traders in Vietnam offered 5% black and broken-grade 2 robusta at a discount of $40 per tonne to the September contract, from a premium of $20 last week as London futures hit two-year highs on tightening supply prospects.

“But almost no deals were made at that price,” said a trader based in the Central Highlands, Vietnam’s largest coffee-growing area.

“Both supply and demand are very weak. Farmers are holding on to their last coffee beans while buyers are seeking supplies in Indonesia.”

London prices settled up $12 at $1,627 per tonne on Wednesday.

Farmers in Vietnam’s coffee belt sold coffee at 34,200-35,300 dong ($1.48-$1.53) per kg, up from last week’s range of 33,400-34,300 dong.

Vietnam’s coffee exports in the first five months of the year were likely down 11.4% from a year earlier to 720,000 tonnes. The country’s coffee shipments in May are estimated at 135,000 tonnes, valued at $248 million, official data showed.

Indonesia’s Lampung province exported 5,575.50 tonnes of Sumatran robusta coffee beans in May, down nearly 41% from the same period last year, data from local trade office showed on Wednesday.

Sumatran coffee prices tumbled, as supply from ongoing harvest jumped this week, traders said.

One exporter offered $60 premium to the September contract. The premium was down from $110 to the July contract last week.

“In a day there could be hundreds of trucks arriving at exporters storehouses to bring in new beans,” the trader said.

Another trader offered $100-$110 premiums to the October to March contracts, compared with $110-$120 premiums to the July contract last week.