(Recasts with more financial data, forecasts)
April 24 (Reuters) - Newmont Mining Corp reported higher-than-expected adjusted earnings on Monday helped by higher production and gold prices as the gold miner also raised its longer-term forecast for output and lowered costs due to expansions at a Ghanaian mine.
The world's second-biggest gold producer by market value said adjusted earnings in the first quarter increased 4 percent to $133 million, or 25 cents per diluted share, from the same quarter in 2016.
That was ahead of analysts' average forecasts of 22 cents a share, according to Thomson Reuters I/B/E/S.
The Greenwood Village, Colorado-based miner, which has mines in the Americas, Africa and Australia left unchanged its gold production forecast for 2017.
But it raised its production forecast for 2018 and beyond to between 4.7 million and 5.2 million ounces on the back of recently-approved expansions at its Ahafo mine in Ghana. Newmont had previously forecast production remaining stable at 4.5 million to 5.0 million ounces in this period.
Newmont said all-in sustaining cost forecasts were unchanged for 2017 and 2018 but longer-term costs would fall to between $870 and $970 per ounce on increased production from Ahafo. Previously Newmont had forecast costs of between $880 and $980 per ounce in this period.
Newmont announced plans on April 20 to extend production at its Ahafo mine by building a new underground mine and expanding plant capacity by 50 percent. (Reporting by Nicole Mordant in Vancouver; Editing by Meredith Mazzilli and Marguerita Choy)