Shares of Australia's largest gold producer, Newcrest Mining Ltd. (NCM), tumbled in Sydney on Friday to a four-year low after the mining firm slashed by 10 per cent its annual production guidance output.

Shares dropped to A$20.16 at 2:42 p.m. local time, or by as much as 7.8 per cent, its lowest since November 20, 2008.

Newcrest announced on Friday it would reduce its gold production output for the 2013 financial year to 2.00 to 2.15 million ounces, owing to mining challenges.

"Primarily as a result of the restricted production capacity at Lihir and continuing challenges with poor ground conditions at Gosowong (Indonesia), the company has determined that the original guidance provided for financial year 2012/13 gold production is no longer achievable," Newcrest said in a statement.

Consequently, 620,000 ounces to 680,000 ounces of gold will be mined from Lihir during fiscal 2013, while Gosowong output will be somewhere between 300,000 ounces to 325,000 ounces, Newcrest added.

Annual production guidance for copper, meantime, remains the same at 75,000 to 85,000 tonnes. Also unchanged were full-year site cost guidance as well as full-year capital guidance.