Tens of thousands of demonstrators poured into Brussels, hoping to swell into a 100,000-strong march on European Union institutions later in the day and reinforce the impact of Spain's first nationwide strike in eight years.

All the actions sought to protest the budget-slashing, tax-hiking, pension-cutting austerity plans of European governments seeking to control their debt.

In an ironic twist, the march in Brussels comes just as the EU Commission is proposing to punish member states that have run up deficits to fund social programs in a time of high unemployment across the continent. The proposal, backed by Germany, is expected to run into strong opposition from France.

“It is a bizarre time for the European Commission to be proposing a regime of punishment,” said John Monks, general secretary of the European Trade Union Confederation, which is organizing the Brussels march.

“How is that going to make the situation better? It is going to make it worse,” Mr. Monks said in an interview with Associated Press Television News.

Unions fear that workers will become the biggest victims of an economic crisis set off by bankers and traders, many of whom were rescued by massive government intervention.

Several governments, already living dangerously with high debt, were pushed to the brink of financial collapse and have been forced to impose punishing cuts in wages, pensions and employment — measures that have brought workers out by the tens of thousands over the past months.

“There is a great danger that the workers are going to be paying the price for the reckless speculation that took place in financial markets,” Mr. Monks said. “You really got to reschedule these debts so that they are not a huge burden on the next few years and cause Europe to plunge down into recession.”

In Spain, Prime Minister Jose Luis Rodriguez Zapatero's Socialist government is under severe pressure because of the hugely unpopular measures put in place to save Europe's fourth-largest economy from a bailout like one that saved Greece from bankruptcy.

The cuts have helped Spain trim its central government deficit by half through July but the unemployment rate stands at 20 percent, and many businesses are struggling to survive.

The strike Wednesday was Spain's first general strike since 2002 and marked a break in the once-close relationship between unions and the Socialist government.

Whistle-blowing picketers blocked trucks from delivering produce at the main wholesale markets in Madrid and Barcelona. Strikers hurled eggs and screamed “scabs” at drivers trying to leave a city bus garage in Madrid.

The salary cuts for civil servants, pension reforms and new laws that make it easier for companies to fire workers were rushed into law quickly in Spain, without traditional negotiations between management and workers.

Greece, which had to be rescued by the euro-nations this spring to stave off bankruptcy, has also been forced to cut deep into workers' allowances, with weeks of bitter strikes and actions as a result.

Bus and trolley drivers walked off the job for several hours while Athens' metro system and tram were to shut down at noon. National railway workers were also walking off the job at noon, disrupting rail connections across the country, while doctors at state hospitals were on a 24-hour strike.

Greece has already been suffering from two weeks of protests by truck drivers who have made it difficult for businesses to get supplies. Many supermarkets are seeing shortages, while producers complaining they are unable to export their goods.

Truck drivers' unions voted late Tuesday to continue their protests against plans to liberalize their tightly regulated profession, despite a government threat to force them back to work or cancel their licenses.

Greece's government has imposed stringent austerity measures, including cutting civil servants' salaries, trimming pensions and hiking consumer and income taxes. Several other EU nations are also planning actions.

In Dublin, a man blocked the gates of the Irish parliament with a cement truck to protest the country's expensive bank bailout. Written across the truck's barrel in red letters were the words: “Toxic Bank” Anglo and “All politicians should be sacked.”

Police arrested a 41-year-old man but gave few other details.

The Anglo Irish Bank, which was nationalized last year to save it from collapse, owes some euro72 billion ($97 billion) to depositors worldwide, leaving Irish taxpayers with a mammoth bill at a time when people are suffering through high unemployment, tax hikes and heavy budget cuts.

Many experts say, no matter what unions try, the towering government debt across the continent will force drastic changes in Europe's labor situation.

“The party is over,” said former EU Commissioner Frits Bolkestein at the financial Eurofi conference in Brussels. “We shall all have to work longer and harder, more hours in the week, more weeks in the year, and no state pension before the age of 67.”

The unions say, however, the party was only there for society's upper crust, and workers are being forced to pay the bills. The crisis has left 23 million people unemployed in Europe, Mr. Monks said.