Vietnam's coffee exports in January jumped beyond the government estimate ahead of a major holiday, official data showed on Thursday, while Indonesia is expected to be busier next week as it nears a mini harvest, traders said.

Farmers in Daklak, the main coffee-growing province in Vietnam, quoted beans at 37,000-37,200 dong ($1.63-$1.64) per kg, traders said, edging down from last week's range of 37,500-37,600 dong per kg.

Traders quoted the 5 percent black and broken grade 2 robusta at a discount of $60-$100 per tonne to the ICE May futures contract, compared with a discount range of $40-$100 per tonne last week.

Vietnam, the world's biggest grower of robusta, exported 200,745 tonnes of coffee in January, a 26.8 percent surge from a month earlier and ahead of the government estimate of 175,000 tonnes, customs data showed.

Exports of the beans would fall to 120,000-130,000 tonnes this month, traders estimate, as the Southeast Asian nation takes a week-long holiday from February 14 for the Lunar New Year celebration.

Vietnam was forecast to harvest 28.5 million bags of coffee in 2017/2018, with estimates ranging from 27 million to 30 million bags, a Reuters poll of 14 traders and analysts showed, up from 24.7 million bags exported during 2016/2017.

In rival Indonesia, the grade 4 defect 80 robusta traded at a premium of $160 to London's March contract, within the $160-$170 premium range that has lasted since mid-December amid depleting stock, a trader said.

"Prices are still stagnated this week, [it] can't go anywhere since demand is not that big," said the trader who is based in the Lampung province, Indonesia's main coffee growing region, adding that trading was expected to pick up next week ahead of a small harvest around March and April.