WARSAW (Reuters) – Poland will close a dozen coal mines from Tuesday for three weeks to stop the spread of the coronavirus among miners, its deputy prime minister said.

The move comes as Poland recorded its largest daily rise in the number of coronavirus cases on Monday, with 599 new infections. Miners account for almost 20% of recorded coronavirus cases in the country.

Two mines operated by state-run JSW and 10 mines owned by PGG group will close for the three weeks. They are all located in Silesia, a major mining region which accounted for more than half of the new cases reported on Monday.

The trade union Solidarity, however, opposed the decision to close the mines, saying it would lead to their permanent closure as the government was already planning to restructure the industry.

“Such action is needed to eventually quell these epidemic outbreaks,” Deputy Prime Minister Jacek Sasin told a news conference.

Miners would receive full pay for the three weeks and coal deliveries would not be affected, he said.

“This decision will in truth lead to the closing of these workplaces,” the Solidarity union said in a statement.

“… Anyone who has an elementary knowledge of the functioning of coal mines knows that you can’t stop these sorts of operations from one day to another without the appropriate technological insurances.”

Poland generates most of its electricity from coal, despite pressure from the European Union to switch to cleaner energy. The pandemic has exacerbated problems facing the Polish coal industry, which is bracing for a restructuring plan expected to be announced by the government in coming weeks.

The Solidarity union questioned why certain mines were being closed when they had fewer cases of coronavirus than others.

Shares in JSW, the European Union’s biggest coking coal producer, initially slumped by 10% as investors expected that the Zofiowka and Pniowek mines, which suffered the highest number of cases and dig mostly higher-value coking coal, would be the ones to close.

However, the state assets ministry later confirmed that the mines that would close would be JSW’s Knurow-Szczyglowice and Budryk mines, which produce mostly thermal coal.

JSW shares closed down 9%.

The PGG mines that will close also do not include those with the highest numbers of infections. However, PGG’s Wujek coal mine, which sources said earlier this month will likely be permanently shut as part of the restructuring, will be among those closing.

“This is a surprise to me that these are the mines to be closed. This may indicate that the government aims to reduce the output of thermal coal,” said mBank analyst Jakub Szkopek.

Sasin said workers at the mines that will be closed had yet to be fully tested for coronavirus.

Poland has now reported 27,160 coronavirus cases and 1,166 deaths, a much lower toll than in some other European countries.