Indonesian coal producer PT Bumi Resources Tbk’s coal sales rose 23 percent in January-June and it is on track to meet this year’s sales target despite heavy rains in its mining areas, a company official said on Wednesday.

Bumi , the largest coal producer in Southeast Asia’s biggest economy, sold 28.4 million tonnes of coal in the first half compared with 23.1 million tonnes a year ago, said Dileep Srivastava, Bumi’s senior vice-president for investor relations.

He said the company’s 6 million tonnes stockpile at the begining of the year had declined as sales outstripped production, but he expected the company to replenish stocks in the second half of the year as the weather improved.

Srivastava did not give details.

“We sold 28.4 million tonnes in the first half, up from 23.1 million last year … and we are on track to meet our guidance for this year of 58 million tonnes,” Srivastava said by telephone.

“This rainfall is normal, that’s why we have a stockpile.”

Indonesia’s main coal mining area of Kalimantan was hit by heavy rains in the first half, which could affect the price of the commodity. Global demand for coal has increased as the world turns to alternative sources of energy as a substitute for oil products.

Indonesia, which has surpassed Australia as the world’s biggest exporter of thermal coal, produced 193.5 million tonnes last year and output is expected to rise 10 percent to around 214 million tonnes this year, an industry group said in May.

Rising exports from Indonesia are expected to help keep a lid on regional coal prices, which have nearly doubled in the past three years due to limited Australian export growth plus rapidly rising demand from China and India.

Bumi Resources is aiming to boost production by more than half over the next four years, reaching 100 million tonnes by the end of the decade.

Bumi agreed in March to sell stakes in two of its biggest mines, PT Kaltim Prima Coal and PT Arutmin Indonesia, to private Indian firm Tata Power Co. for $1.3 billion.