Top Indonesian coal miners like Bumi Resources are expected to report strong results for the first half of this year, with higher coal prices more than offsetting increasing costs of production from a jump in fuel prices.

“Fuel prices are rising, but Bumi expects its cash margins to continue increasing as coal prices are expected to rise far more than the input costs,” said Dileep Srivastava, a director at Bumi. “Hence, we expect an outperformance in operations for fiscal year 2011 and going forward.”

Bumi, the country’s largest coal producer and the world’s biggest exporter of thermal coal, booked a 35 percent increase in revenue to $2.7 billion in the first half, even though output remained steady from a year earlier at 30 million tons. The coal, however, was sold at an average realized price of $91 per ton, a 36 percent rise from the year before.

Other ratios such as gross margins, operating profit, net income and earnings before interest, tax, depreciation and amortization (ebitda) are expected to be sharply up in the first half of this year, Dileep said. Bumi will report its audited income statement for January to June by the end of next month.

“With global coal supply falling far short of burgeoning demand from China, India and Indonesia, and with a small short-term offset from Japan, the forward price curves indicate that benchmark coal prices will continue to be strong, ranging between $122 per ton FOB presently and rising conservatively to $133 per ton FOB over the medium term,” Dileep said.

This prompted a bullish outlook that full-year financial performance could surpass expectations. This year, Bumi expects production sales to reach 65 million to 66 million tons at an average price of $90 per ton FOB. That is compared to last year’s 60 million tons at $71 per ton FOB.

“All in all, 2011 and beyond we are eyeing prospects of a major outperformance,” Dileep said.

Separately, Adaro Energy, the country’s second-largest coal producer, is forecast to book a 58 percent increase in revenue in the first half, said Reza Priyambada, an analyst at Indosurya Asset Management in Jakarta. The miner has not yet announced its first-half results.

Adaro said its coal sales rose 10 percent to 24.02 million tons in the first half of this year from 21.75 million tons in the same period last year. The company has set a production target of up to 48 million tons.

“We are on the right track this year,” Garibaldi Thohir, its president director, said on Friday. “Coal production is above last year’s production.”

Thohir said rising coal sales were expected to boost the company’s revenue.

Adaro’s coal sales increased 20 percent in the second quarter this year from the first quarter as the company booked purchase agreements with several countries including India, China, South Korea and Thailand, which became its newest customer in the second quarter of this year.