IAMGOLD Corp.'s net loss attributable to shareholders in the fourth quarter of 2017 widened to US$17.7 million, or 4 U.S. cents apiece, from a net loss of US$5.3 million, or 1 cent apiece, in the year-ago quarter.

The company slipped further into the red mainly due to a US$30.3 million tax charge in the quarter, compared to a US$1.0 million tax gain a year ago.

Revenue in the three-month period increased to US$291.1 million, compared to US$252.5 million a year ago, on the back of higher gold sales volumes and realized prices, according to the Feb. 21 release.

The company sold 230,000 ounces of gold at an average of US$1,277 per ounce in the quarter, compared to 218,000 ounces sold at US$1,190 per ounce in the prior-year quarter.

Production in the period increased to 228,000 ounces at all-in sustaining costs of US$1,071 per ounce, compared to year-ago output of 215,000 ounces at all-in sustaining costs of US$995 per ounce.

For the full year, net earnings attributable to shareholders surged to US$501.6 million, or US$1.08 per share, from net earnings in 2016 of US$52.6 million or 13 cents per share, mainly due to US$524.1 million of impairment reversals at the Cote gold project in Ontario and the Rosebel mine in Suriname.

Revenue in the full year rose 11% year over year to US$1.09 billion on the back of higher sales at the Westwood, Essakane, and Rosebel mines, as well as a higher realized gold price.

The company produced 882,000 ounces of gold in 2017 at all-in sustaining costs of US$1,003 per ounce, an increase over the 813,000 ounces produced a year ago at all-in sustaining costs of US$1,057 per ounce.

In 2018, IAMGOLD is targeting production of between 850,000 and 900,000 ounces at all-in sustaining costs of between US$990 and US$1,070 per ounce.