Spain Hobbled by General Strike Juan Medina/Reuters Protesters in Madrid shouted slogans during a general strike on Thursday. MADRID - Heavy industry and large parts of the transportation network were disrupted on Thursday by Spain's first general strike since the Popular Party of Prime Minister Mariano Rajoy came to power late last year. The strike was called by Spain's two main trade unions to protest a recent overhaul of labor rules that makes it less costly for employers to hire and fire workers. It came on the eve of Mr. Rajoy's presentation of Spain's 2012 budget, which is expected to contain about €20 billion, or $26 billion, in additional spending cuts and tax increases to help Spain meet deficit targets it agreed to with the European Commission. Spain is entering its second recession in three years with 5.3 million people, almost 23 percent of the work force, unemployed - more than double the European average. Support for trade unions, however, has dwindled in recent years because of their failure to prevent the surge in unemployment and controversy surrounding the unions" reliance on government subsidies rather than contributions from members. Late Thursday afternoon, the Interior Ministry said that 176 people had been arrested by the police across the country, mainly after scuffles on picket lines that also left some people lightly injured. But central Barcelona was also the scene of violent clashes between the police and protesters, who smashed shop windows and blocked streets by setting garbage containers on fire, as well as a Starbucks cafe. Meanwhile, the unions and the government disagreed over the impact of the strike. Union leaders called the strike a success, with an estimated participation of about 77 percent. Cándido Méndez, the secretary general of the UGT, said the strike left Mr. Rajoy with no other option than revising the labor overhaul. The government's policies, Mr. Méndez argued, meant that Spain was now "pushed to the limit." The government, however, refused to confirm the participation figure and instead asserted that the economic impact of the strike was below that of a previous general strike in September 2010, when unions protested against earlier austerity measures introduced by the then Socialist administration of Prime Minister José Luis Rodríguez Zapatero. Fátima Báñez, the labor minister, said Thursday that the government would not yield to union demands and alter its recent labor legislation overhaul, calling instead the government's reform agenda "unstoppable." Red Eléctrica, the operator of the national electricity grid, said that consumption on Thursday was about 16 percent below normal levels. The strike almost brought to a standstill production across the automotive sector, with workers staying away from factories owned by Ford, Volkswagen and other car makers. The mining sector was also shut down by the strike, as was the textile factory of Inditex, the clothing retailer, in its home city of La Coruña. Yet most banks, restaurants and leading retailers like El Corte Inglés stayed opened for business. While some flights were canceled, major airports led by that in Madrid were also functioning Thursday. Protesters had scheduled more than 100 marches across Spain on Thursday. The largest one, in Madrid, began peacefully at 6:30 p.m. and was due to end in Puerta del Sol, the central square that was the scene last year of a lengthy, student-led protest against established political parties and other institutions and their failure to prevent the economic crisis from deepening. Francisco Pérez, a former union representative who recently retired after three decades in the administration of Madrid's airport, called Thursday's strike a "useless response to the problems that Spain is facing." Mr. Pérez was referring to a recent controversy surrounding José Ricardo Martinez, a former railroad technician and secretary general of the UGT in Madrid, who has been receiving almost $240,000 a year as a board member of Bankia, a savings bank. Despite the surge in Spain's unemployment and the collapse of its property sector, social unrest has so far been much more limited in Spain than in a country like Greece, which has been at the forefront of the European debt crisis.