The giant mining concerns at the core of the Australian resources sector have posted further gains to their iron ore production levels.

Both BHP Billiton and Rio Tinto have announced gains in iron ore output for the quarter just ended, despite production being hampered by seasonal weather conditions in key mining regions.

BHP’s iron ore output in the three months to March 31 came in at 49.6 million tonnes, edging ahead of analysts’ expectations of 48.3 million tonnes, as well as advancing a hefty 23 per cent upon the prior corresponding quarter.

According to CEO Andrew Mackenzie, BHP’s production of iron ore and metallurgical coal has reached unprecedented levels during the first nine months of the fiscal year.

On the back of these bumper results, the mining giant has lifted its full-year production guidance for iron ore by five million tonnes to 217 million tonnes.

The move goes beyond the expectations of even the most optimistic of analysts, and marks the second occasion this year that BHP has lifted its iron ore production guidance.

Analysts point out that this increase in iron ore production guidance bodes well for BHP’s annual performance, given that the division comprises approximately half of the miner’s earnings.

Rio Tinto similarly announced that its first quarter iron ore output in its core operations hit 52.39 million tonnes, for an 8 per cent year-on-year gain compared to the 48.25 million tonnes produced in the previous corresponding period.

This increase was achieved despite highly adverse weather conditions in the Pilbara, where port and rail operations were closed in December as a result of Cyclone Christine, and the first two months of the year were hampered by heavy rainfall.

Global iron ore production for Rio Tinto also achieved an 8 per cent year-on-year increase, hitting 6.4 million tonnes.

“Rio Tinto has started the year with a series of performance records as we continue to drive productivity gains across our operations,” said CEO Sam Walsh.

Rio Tinto’s full-year global production guidance remains unchanged, forecasting annual output of 295 million tonnes from its mines in both Australia and Canada.