MELBOURNE, Jan 28 (Reuters) - Australia's Fortescue Metals Group FMG.AX said on Thursday it had cut costs to $15 a tonne in December, six months ahead of target, helping it to stay in the black following a 35 percent plunge in iron ore prices last year.
The world's fourth biggest iron ore producer shipped 42.1 million tonnes in the December quarter, up 2 percent from a year earlier.
"Cost performance is well ahead of guidance with the targeted FY16 exit rate of $15/wmt (wet metric tonne) achieved in December 2015," Fortescue said in its quarterly report.
The company slashed costs in the December quarter to $15.80/wmt from $16.90 in the previous quarter and down 45 percent from a year earlier.
Fortescue also cut its net debt by $500 million to $6.1 billion in the December half, after buying back $750 million worth of notes that had been due in 2019 and 2022 at a discount and reducing its interest bill.