Shares in gold miner Centamin (LON:CEY) fell over 6 percent at market open on Monday, after reporting a significant drop in gold production.

The company said production had fallen by 25 percent in the second quarter, after reporting low grades at its mine in Egypt. It is undergoing a “transitional zone” at its Sukari mine but expects production to be “materially stronger” in the second half of the year.

Centamin maintained current guidance figures of between 505,000 to 515,000 ounces of gold, after slashing expectations in May.

“We have experienced several challenges this year, resulting in the revision of our full year guidance in May,” Andrew Pardey, chief executive, said.

“I am pleased to report progress throughout June in the open pit, where mining has begun to access improved grades as we are currently mining through the lower areas of the transitional zone and into the sulphide ore, which will be mined in the third quarter and onwards for the next four years.”

The miner was one of the biggest fallers of the miners on Monday. Sirius Minerals (LON:SXX) rose 0.6 percent after signing up to Redcar Bulk Terminal to provide port and ship loading services for up to 10m tonnes per annum of potash.

Shares in Centamin are currently trading down 6.46 percent at 110.15 (0922GMT).