Fortescue Metals has more than tripled its half year profit to a record $US1.71 billion ($A1.9 billion) and maintained its production targets.

The world’s fourth biggest iron ore miner’s profit in the six months to December 31 was up from $US478 million in the same period a year earlier, as it ramped up its production.

Fortescue shares fell however, and were down 11 cents at $5.87 at 1401 AEDT.

Chief executive Nev Power said the record result underlined the success of Fortescue’s strategy to construct new capacity, ramp up production and drive down costs.

“The ongoing strong demand for our products has allowed us to accelerate debt repayment, de-risk the balance sheet and increase returns to our shareholders,” Mr Power said in a statement.

Half year revenue was $US5.8 billion, up 77 per cent from $US3.3 billion in the same period a year earlier.

Shipments were up 51 per cent from the prior period, and it maintained its full year shipment guidance of 127 million tonnes of iron ore, but said it remained sensitive to weather.

Bad weather in January led to a reduction in Fortescue’s full year forecast for iron ore it shipments to the lower end of its previous guidance range.

The Pilbara miner also said it remains on track to deliver iron ore at a rate of 155 million tonnes per annum (mtpa) by the end of March 2014.

Fortescue announced a 10 cent dividend, after paying no dividend in the prior period.

The company said it has “significant flexibility” to make voluntary debt repayments, or refinance debt before it matures.

Since November 2013 it had committed debt repayments of $US3.1 billion ($A3.44 billion), and the repricing of a term loan was delivering interest savings of about $US300 million ($A333.06 million) per annum.