Czech state-owned hard coal mining group OKD has shut down all of its mining operations for six weeks as it battles an outbreak of coronavirus infections. The mines, in the country’s east near the Polish border, have been the Czech Republic’s main hot spot of new cases recently.

Three deep mines will be shut down in addition to the first location where the outbreak started and was shut down on May 22.

News agency CTK reported that blanket testing of 3,403 employees at OKD’s two CSM mines showed 704 positive cases, with no or mild symptoms.

OKD supplies the northeastern Czech industrial region, near the borders with Poland and Slovakia, with 4 million metric tons of coking and thermal coal per year.