SYDNEY: The world's biggest miner BHP Billiton fired a warning over the economic recovery on Wednesday despite smashing forecasts with half-year profits of 6.14 billion US dollars.

BHP said the global economy had hauled itself out of the doldrums of the financial crisis but cautioned that advanced countries were expected to lag growth in the developing world.

First-half profits to December more than doubled -- up 134 percent -- from the 2.62 billion US dollars recorded a year earlier, as emergency government stimulus prompted a recovery in demand.

"Despite this positive momentum, we remain cautious about the speed and strength of the global recovery across the developed world," BHP said in a statement.

"It appears that stimulus measures that supported the recovery have not fully addressed structural issues such as weak labour markets and excess production capacity in developed economies."

BHP said strong sales volume growth had boosted its bottom line along with December's 340 million US dollar sale of the Ravensthorpe mine in Western Australia, the source of a goodwill impairment charge in 2008.

Profit excluding exceptional items fell seven percent to 5.7 billion US dollars. BHP announced a dividend of 42 US cents per share, up 2.4 percent on a year earlier.

"Given the volatility that we had in the 12 months preceding, we are very pleased with these results," chief executive Marius Kloppers told reporters.

BHP said global conditions had improved with the United States and Europe lifting their dismal industrial output while China returned to double-digit growth and India proved resilient.

It said it would keep a close eye on China's credit-tightening and noted that many of its orders came from restocking, warning that "real end demand still appears sporadic".

"Notwithstanding our caution in the short term, over the long term we continue to expect emerging economies' growth to strongly outperform the developed countries as they follow a path of continued urbanisation and industrialisation," BHP said.

"Any effects on commodity demand due to potential weakness in developed countries are likely to be offset over time by continuing growth as China and India urbanise and industrialise," it added.

IG Markets research analyst Ben Potter said the profit announcement had "obliterated expectations".

"The comment that ?supply may struggle to keep pace with demand? will garner a lot of attention as it bodes well for higher sustainable commodity prices," he said.

"Also, the fact that the result was driven by higher volumes as opposed to higher prices should please the market."

Dual-listed BHP was trading at 40.59 dollars in Sydney after the announcement, a rise of 1.86 percent.