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 cheaper 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 $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.