Spanish coal miners burned tyres and blocked roads on Monday in a sector-wide strike to protest against subsidy cuts that they say threaten tens of thousands of jobs.

Thousands of people marched in the northern city of Leon and another major demonstration was planned in Langreo in the northern mining region of Asturias, the latest in a month of protests.

The cash-strapped central government has slashed subsisidies to the coal sector this year to 111 million euros ($142 million) from 301 million euros last year, part of wide-ranging cuts to lower its deficit.

The miners say this is unfair especially when the government has also sought billions of euros to stabilise its banking sector.

"The crisis is a useful excuse for taking money from workers and giving it to the banks," said one retired miner, Vicente Turrado, 54, in the town of Langreo, which was quiet as businesses shut down on Monday.

Protests in the northern coal mining regions over the past few weeks have turned radical, as striking miners have clashed with riot police daily.

Masked miners put up fresh barricades across the road Monday near a mine in Mieres, Asturias.

"It is the only way to make the politicians listen to us," said one 24-year-old miner in a mask, who asked not to be named. "If the mines close, everything will close."

Seven people were injured in clashes Friday near Mieres, where a handful of miners are hunkered down deep underground, refusing to come up in protest.

Spain's coal mining industry has been contracting for decades, with its direct workforce shedding more than 40,000 people over the past 20 years.

Spain has around 8,000 coal miners and the sector indirectly provides jobs for up to 30,000 others, unions say. They say the subsidy cuts will close the coal mines, which rely on state aid to compete with cheaper imports.

Like other European countries, Spain has committed to gradually close non-profitable coal mines in the next few years.