The general strike, which began at midnight, has already resulted in the arrest of 58 people in various picket lines around the country.
Large numbers of pickets tried to prevent buses leaving depots in the main cities this morning, with occasional violent clashes, leaving one woman protester and two police officers slightly injured. Access to the Renault factories in Valladolid and Palencia, the Seat factory in Martorell and the Volkswagen factory in Navarra, has been blocked by human barriers and walls of burning tyres.
Electricity supply companies reported a 25% drop in demand at 8.30 this morning, compared with a normal workday morning and traffic police are reporting less traffic on the roads, particularly along the main arteries leading into the bigger cities like Madrid and Barcelona.
Road, rail and air transport are all due to be affected, with domestic and European flights cut to a fraction of their usual volume. Under an agreement between the government and the unions, at least a minimum service of a third of local trains and buses is due to run, with one in 10 domestic and one in five European flights.
Spanish workers, led by the country's two biggest unions, the UGT and CCOO are holding a general strike to protest against labour reforms which the new government hopes will help cut unemployment, but which they believe will make it easer for companies to fire employees. The new legislation, approved in February, also reduces maximum severance pay to 33 days' salary for each year worked, compared with the current 45 days.
The government insists the reforms will create a more flexible system for businesses and workers, in a country with a stagnant economy that needs to start creating jobs. With the EU's highest rate of unemployment, Spain is under pressure to reduce its budget deficit and bring its public finances under control. Mariano Rajoy's conservative government is to unveil measures on Friday to save tens of billions of euros. The strike is the government's first big challenge since taking office.
Protest marches have been planned in a number of major cities around the country this evening. Ignacio Fernandez Toxo, leader of the CCOO trade union, said the strike was "a just response to a brutal reform of our system of labour relations".