BHP Billiton, the Anglo-Australian miner trying to buy rival Rio Tinto for about $150bn, said its third-quarter iron ore output rose 22 per cent, driven by strong Chinese demand for the commodity used to make steel.

The increase in iron ore output to 28m tonnes in the March quarter from the same time last year outstripped the near 16 per cent quarterly rise to 39m tonnes reported by Rio Tinto recently.

It comes as the takeover battle moves into increasingly hostile territory, with both sides talking up their growth prospects.

Marius Kloppers, BHP chief executive, on Tuesday made an outspoken attack on his mining rival’s past underperformance and growth prospects, and rounded on Rio’s chief executive, saying: “Tom Albanese has been comprehensively outperformed [by BHP] in terms of volume growth, earnings per share growth, total return for shareholders and share price performance.

However, BHP reported mixed production results elsewhere, with quarterly declines in aluminium, copper, nickel and diamonds. The main disappointment was in coking coal, where output dropped 25 per cent after floods in mines in Queensland.

Although coal production has resumed at the mines, output remains “constrained” as mines move back to full capacity, BHP said.

Rio also reported a mixed set of quarterly production figures, which showed its iron ore production in Western Australia had been hit by cyclones and power cuts.

BHP, too, has suffered from what Mr Kloppers this week described as “acts of God”, including earthquakes in South America and floods in Queensland.

BHP said production of its 12 main commodities rose in the nine months ended in March, with a “significant increase” in petroleum.

Mr Albanese last week sought to highlight Rio’s dominant position in aluminium against BHP’s “60th ranked” oil and gas business.

BHP countered that the petroleum business is one of its strongest and is delivering high margins as oil trades above $115 a barrel.

BHP’s total petroleum product output rose 10 per cent to 93.3m barrels of oil equivalent in the nine-months period, while third-quarter production rose 19 per cent to 32.7m boe.

The Melbourne-based group said it was on track to deliver a 10 per cent rise in petroleum volume growth for the full year.

Crude oil, condensate and natural gas liquids production increased 13 per cent over the nine months, and 39 per cent over the quarter.

However, growth from new projects was partly offset by declines in some fields and interruptions due to cyclone activity in Western Australia.

BHP shares were up 2.3% at A$44.53 early in the afternoon in Sydney.

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