JAKARTA: Indonesia's Bumi Resources , Asia's biggest thermal coal exporter, posted a net loss in the fourth quarter on foreign exchange losses and higher interest and tax charges.

The firm's fourth quarter net loss was $8.3 million, compared with a $115.58 million profit in the same period a year earlier, according to Reuters calculations based on published full-year and nine month results.

Bumi, the leading Indonesian miner in the world's biggest exporter of thermal coal, sees coal demand from Japan rising 17 percent this year. It saw 2011 thermal coal production rise to 65.9 million tonnes, versus 60 million tonnes the previous year, though its full year profit underperformed expectations.

Bumi on Saturday posted 2011 net profit of $220.5 million, compared with a heavily restated net profit of $207.1 million in the previous year, and analysts' forecasts for 2011 of $382.4 million, according to Thomson Reuters' I/B/E/S.

Its full year tax charges were $383.5 million versus $264.43 million in 2010, a Bumi director told Reuters.

The Jakarta-based miner's 2011 revenues were $4.0 billion, compared with a heavily restated $2.9 billion a year earlier.

Bumi, with a market capitalisation of $7.8 billion, is controlled by the politically-connected Bakrie Group, which joined forces with the Rothschild banking dynasty to list Indonesian coal assets in London via Bumi Plc.

Bumi shares fell more than 28 percent in 2011 to underperform a Jakarta index up 3.2 percent in the same period.