The 48-hour strike began on Wednesday, involving nearly 10,000 miners and bringing mines to a halt in four Spanish regions.
A strike shut down several Spanish coal mines on Thursday as miners protested against delayed salaries and European Union plans to abolish subsidies for the sector.
Trade unions also announced protest marches starting in several places in the northern Asturias region and converging on the regional capital Oviedo.
The 48-hour strike began on Wednesday, involving nearly 10,000 miners and bringing mines to a halt in four Spanish regions. Miners have been protesting for several weeks over two month’s worth of unpaid salaries for around 2,600 employees, and against EU plans to withdraw coal mines subsidies by 2014.
Spanish coal is more expensive and polluting than imported coal, forcing the government to subsidize it.
Two hundred miners are staging a nine-day protest march, while several others are on hunger strike, including a group of four who are inside the Industry Ministry in Madrid.
Other groups of demonstrators are holed up in two northern mines at a depth of more than 500 metres.
The Spanish coal mining sector employs about 8,000 people, down from more than 50,000 people 25 years ago.