Indonesia's Ministry of Energy and Mineral Resources set its June thermal coal reference price -- also known as Harga Batubara Acuan or HBA -- at $52.98/mt, down 13.3% on the month and 35% on the year.

The HBA is now close to a four-year low, with the figure previously reaching $53/mt in July 2016, S&P Global Platts data showed."A stagnated global economy has reduced Chinese and Indian seaborne coal demand, coupled with the high domestic stockpiles these countries are currently consuming, the HBA has edged lower on the month," according to a ministry spokesman.

The ministry had set the price for May at $61.11/mt, and for June 2019 at $81.48/mt.

The HBA is a monthly average price based 25% each on Platts Kalimantan 5,900 kcal/kg GAR assessments, Argus-Indonesia Coal Index 1 (6,500 kcal/kg GAR), Newcastle Export Index (6,322 kcal/kg GAR) and globalCOAL Newcastle (6,000 kcal/kg NAR).

In May, the daily Platts FOB Kalimantan 5,900 kcal/kg GAR coal assessment averaged $49.84/mt, down 10.4% from $55.60/mt in April.

The HBA price for thermal coal is the basis for determining the prices of 77 Indonesian coal products and calculating the amount of royalty producers have to pay for each metric ton of coal sold.

It is based on 6,322 kcal/kg GAR coal with 8% total moisture content, 15% ash as received and 0.8% sulfur as received.