Fortescue Metals Group said it has loaded 8.5 million tonnes of iron ore and achieved an annualised 100 million tonne production run rate in the last month of 2012.

The iron ore focused company said the December run rate was 23 per cent higher than its previous monthly record set in May 2012.

"The increased throughput was a result of a number of milestones that occurred in December, including the ramp up of the second ore processing facility at Christmas Creek mine, first ore from the Solomon mine and the opening of the Fortescue Hamersley Rail Line," the company said in a statement.

Fortescue said it remained on track to reach its near term target rate of 115 million tonnes per annum this quarter as it looked to take annual production to 155 million tonnes by December 2013.

Recent enthusiasm for debt-laden Fortescue comes a week after it announced work would resume on expanding the Kings deposit at its Solomon iron ore mining hub in January after a rebound in commodity prices.