(REUTERS) -- Canada's Nevsun Resources Ltd expects gold production at its Bisha mine in Eritrea to nearly halve in 2012 due to a cut in its reserve estimate.

The company expects to produce 190,000 ounces to 210,000 ounces of gold this year, compared with 379,000 ounces it produced last year.

Nevsun said the resource in portions of Bisha were overestimated.

The company also expects to complete the copper phase expansion project in 2012 and start production in mid 2013.

While production for 2012 is lower than expected, Nevsun estimates the cash flow generated this year from the oxide deposit will be more than sufficient to fund the copper plant to completion.

Bisha mine is one of the highest grade open pit base metal deposits in the world and has a mine life in excess of 12 years.

Nevsun shares closed at C$6.34 on Monday on the Toronto Stock Exchange.