Though the strikes will be held on the same day, their motives are very different and they are unlike typical industrial action in that they enjoy the tentative support of management.

In the Trbovlje-Hrastnik coal mine, which has been in the process of being wound down since 2000, the miners will demand back pay in an 8-hour strike, according to the head of the in-house union, Anton Lisec.

The decision came after a bank blocked the company's accounts due to mounting debt, making it impossible for the company to pay the remaining 150-odd workers after 135 were laid off at the start of the year.

The miners will not only demand pay, they are also joining the management in demanding of the government that the mine, slated for full closure next year, remain open through 2018.

This would reassure banks, which are owed some EUR 15m, according to the director of RTH, the company that manages the mine, Bojan Jelen.

The company petitioned the government late last year to extend the closure works but it has not yet received a response.

Meanwhile in Velenje, the biggest functioning coal mine in the country with an annual output of almost four million tonnes of lignite coal, miners will stage a two-hour token strike.

Pay is a part of their demands, though they only want full payment of the holiday allowance for last year, not just the statutory minimum prescribed by law.

However, the strike in Velenje is part of rising tensions in HSE, the biggest power utility in the country, which owns the coal mine as well as the Šoštanj thermal power plant that buys all the coal mined there.

Workers in Velenje insist that contracts with Šoštanj be renegotiated as the current coal price makes it impossible to break even or to raise the low wages of miners.

If the price of coal rises, however, the already questionable economics of the new unit at Šoštanj, under construction and currently valued at EUR 1.4bn, would collapse.

The Velenje coal mine trade union thus demands that "internal relations in HSE Group be sorted out", but reactions from HSE suggest this is unlikely.

HSE director Blaž Košorok said earlier this week that the coal mine needed to offload non-core activities that he said were weighing down on the company's bottom line.

Sales of textiles and tourist services do not belong in the coal mining business and are largely responsible for the situation, he was quoted as saying in a HSE press release.

Indeed, Premogovnik Velenje, the company that manages the coal mine, operates the Golte ski resort, a retirement home, and a company making protective gear for the mining industry.

Premogovnik Velenje retorted that extensive restructuring had already been undertaken in the past two decades, with management at group level to blame for the mess.

"In the past year we've witnessed poor coordination and management in HSE Group, at least as far as Premogovnik Velenje is concerned," the company said.