Despite reporting a 6.3% increase in third-quarter silver production, Mexican precious metals miner Fresnillo on Wednesday lowered its production forecast for the year, citing “continued challenges” at the Saucito and Fresnillo mines.

The London-listed company reported that the third quarter’s silver production failed to meet its expectations, prompting management to lower its guidance for the year to between 62-million ounces and 64.5-million ounces, from a previous guidance of 64.5-million ounces to 67.5-million ounces.

Fresnillo, however, marginally increased its gold production guidance to between 920 000 oz and 940 000 oz, from its previous guided range of 900 000 oz to 930 000 oz.

“Gold production continues to beat expectations and we are once again revising our guidance upwards following another strong quarter, in particular at our Saucito and Noche Buena mines where volumes exceed targets. Though silver production is up against all comparable periods, we are revising full year silver guidance following continued challenges at the Fresnillo and Saucito mines. These are world-class, tier-one silver assets, and we remain both determined, and confident, given the actions we are taking, that we will deliver a better performance in the last quarter and in 2019,” CEO Octavio Alvidrez said.

During the third quarter, silver production at the Fresnillo mine suffered as a result of limited access to higher grade areas, resulting from contractor-led delays in development and preparation. The company has appointed a new contractor, which has begun operating and said that this should increase future development rates.

The mine also delivered lower-than-expected ore throughput and ore grades in some areas, which Fresnillo is addressing by an infill drilling programme to enhance the accuracy of the geological model.

At the Saucito mine, quarterly silver production was lower as a result of lower ore grades at two high-grade stopes. An infill drilling programme is also under way to increase the accuracy of the geological model.