Global miner Rio Tinto on Wednesday said it had agreed to sell its 40 per cent stake in the Bengalla coal mine in Australia to New Hope Corp for $606 million, the latest shuffle of Australian coal assets amid a sector-wide downturn.

Bengalla is the smallest of three coal mines in the Hunter Valley near Sydney in which Rio Tinto is a stakeholder. It produced 8.6 million tonnes of coal in 2014.

New Hope, capitalised at A$1.37 billion ($959 million), said last week it was hunting for acquisitions after reporting a 25 per cent rise in annual profit to A$51.7 million ($36.1 million) before one-offs as cost cuts outweighed a drop in sales despite energy coal prices plunging to six-year lows.

New Hope's stock was 2.7 per cent higher at A$1.70 ($1.19) at 0101 GMT (2101 EDT) on Wednesday.

Analysts at Macquarie and Morgan Stanley said Rio had fetched a strong price for the Bengalla stake relative to their valuations of its coal assets.

Rio has been looking to offload less profitable businesses to ensure it can stick to a promise to raise dividends and focus on iron ore and copper mining amid a broad slump in commodities prices caused by slowing economic growth in China.

Rio, advised by Deutsche Bank, earlier this year put all its coal stakes in the Australian state of New South Wales up for sale.

Until recently Glencore was regarded as a front runner for possible purchases as it also mines coal in the same area.

But those prospects are fading as concerns over its debt mount and some analysts speculate it could begin selling its own mines.

Glencore has said it will suspend dividends, sell assets and raise cash, among other measures, to cut its $30 billion debt pile and protect its rating after the prices of its main commodities fell.

As part of the Bengalla sale, Japan's Mitsubishi Corp and Rio have agreed to disband a coal joint venture in the Hunter Valley and will each take direct stakes in mines previously owned via the venture, potentially making it easier for Rio to sell its remaining stakes.

Rio declined to comment on whether it was still looking to sell any of the stakes in those bigger mines. - Reuters