Workers across the European Union have launched an unprecedented string of strikes in a co-ordinated battle against austerity cuts on Wednesday.
The strikes are intended to paralyse factories and public sector offices, and have grounded more than 700 flights. Organisers are urging national leaders to abandon fiscal austerity measures and address growing social anxiety.
Walkouts are expected in Spain, Greece, Portugal and Italy, with other protests planned in Belgium, Germany, France and the United Kingdom.
It is the first time unions have engaged in simultaneous strikes across the continent, said the European Trade Union Confederation, which organised the "Day of Action and Solidarity".
Unions in Spain, the eurozone's fifth-largest economy, and Portugal, ranked 14th, started strikes at midnight to protest against austerity measures that have combined tax rises with cuts in salaries, pensions, benefits and social services.
Spain, where one in four workers is unemployed in a deep recession, is holding its second general strike in eight months to protest against severe budget cuts.
Al Jazeera's Asad Hashim, observing the protests in Barcelona, said that nearly 10,000 protesters marched peacefully chanting slogans against the budget cuts.
Hashim said that some "did throw pain on the façades of businesses that did not observe the strike. They also blew airhorns outside the doors of such businesses, until they closed their shutters. They also periodically exploded small smoke bombs."
He estimated that between 60 and 70 per cent of businesses appeared to have closed in observance of the strike.
Police, reported Hashim, are "out in force but don't seem to be confronting protesters".
The scene was more tense in Madrid.
In the first reported clashes of the day, picketers and police fought at a Madrid transport depot, where demonstrators were trying to stop buses from leaving.
There were outbreaks of violence in other Spanish cities as well, and the interior ministry said several arrests had been made.
In the main squares of Madrid, the main unions strung up banners declaring" "They are taking away our future!" They deployed pickets overnight at airports, markets and bus and railway stations.
"We are launching a day that will be a milestone in the history of European unionism," said Ignacio Fernandez Toxo, head of the country's largest trade union, the CCOO.
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Our correspondent, Tim Friend, reporting from Madrid, said that unions there claim a 78 per cent participation rate in the strikes.
"There have been some clashes between police and protesters. The latest figures we have are 70 people have been arrested, 34 injured - none of them seriously," said Friend, adding that the protests have been "largely peaceful."
Friend also reported that public transport had been "very badly hit", with flights cancelled and ports "at a standstill".
In neighbouring Portugal, Lisbon's metro service was out of service on Wednesday morning, while ferries across the River Tagus and trains across the country ran skeleton services. Refuse collection also ground to a near halt.
Hospital staff joined the action, with up to 90 per cent of staff reportedly abiding by the strike call.
Portugal's unions have called marches and rallies in about 40 towns and cities against the centre-right government's austerity policies.
Nick Spicer, reporting from Lisbon, says that the strikes are not largely backed there, with the second largest union refusing to support the stoppage.
Legislation in both Spain and Portugal requires workers to provide a minimum service in essential industries, but airlines cancelled many domestic and international flights.
Iberia, Iberia Express, Air Nostrum, Vueling, Air Europa and easyJet cut more than 600 flights, including 250 international routes. Ryanair said it had not yet scrapped any flights.
Greece, at the epicentre of the eurozone's debt crisis, is witnessing protests against the latest round of government cuts, while Italian unions have called a four-hour walkout.
Union-led rallies supporting the day of action are expected in France, Belgium and in Poland, where workers decry "social and wage-dumping" in their country.
Al Jazeera's Barnaby Phillips, reporting from Athens said that the march and strike there are "done and dusted" and that strikes and protests have become a common occurrence in Greece.
"So it wasn't a particularly exceptional day in Athens," said Phillips.
However, the Greek government projects that the economy will continue to shrink through 2013 by another 4.5 per cent and that the outlook is "extremely bleak".
Train services between France, Germany and Belgium have been disrupted, with Belgian rail workers participating in the work stoppage in solidarity with strikingg workers in other European countries.
In the Italian capital of Rome, students and workers have been marching against severe spending cuts, with one banner showing German Chancellor Angela Merkel dressed in a Nazi uniform.
Riot police fired tear gas at protesters as clashes broke out during one demonstration there. Armed with makeshift shields painted with anti-austerity slogans, the protesters hurled objects towards police lines.
Several people are believed to have been injured but authorities have not released any official numbers.
In Germany, viewed by many as the paymaster behind the austerity drive, the union federation DGB has called protests across the country, including in Berlin and Frankfurt.