Centerra Gold said workers at its Kumtor mine in the Kyrgyz Republic are on strike over pay and production has been suspended.

The company said the strike is illegal because there is a collective agreement that will expire by the end of the year.

Kumtor Operating, which runs the open-pit mine, said miners demanded a 100% pay increase and rejected the company’s proposal of a 25% pay rise.

The Kumtor mine, located in the Tien Shan mountains, accounted for a quarter of Kyrgyzstan’s industrial output last year and a third of all exports in the former Soviet Republic.