Spanish workers are staging a boisterous 24-hour general strike to protest the government's sweeping labor reforms and a new round of austerity measures the government plans to unveil on Friday.

Protests in Madrid Thursday disrupted public transportation and factories and sharply curtailed flights into and out of Spain. The country's Interior Ministry said at least 58 demonstrators were arrested, largely for attempting to block bus service, and nine were injured in scuffles.

Spanish unions are challenging the three-month-old conservative government of Prime Minister Mariano Rajoy, especially its changes in labor rules. The new regulations make it easier for companies to lay off workers and cut their wages.

Some of the protesters carried signs saying, “Work Reform, No.” One protester, a rail worker, said the rules gave employers an unfair advantage over workers.

“I'm on strike because of the labor market reform. They left us unprotected and they give the businessmen the tools to crush us. We thought that we have to mobilize because this (labor market reform) is an historical loss.”

Spain's economy is struggling and is headed into its second recession since 2009. Its jobless rate — 23 percent — is the highest in the 27-nation European Union.

But the government is under pressure from its European neighbors and international financial markets to further cut spending and meet deficit goals. On Friday, the government is set to announce billions of dollars of new spending cuts in its 2012 budget.

Finance Minister Cristobal Montoro said it did not matter how many workers participated in the strike, but whether the country can regain its economic footing. He said the government “is not going to yield.”