ISTANBUL – Workers around the world united in anger during May Day rallies Wednesday — from fury in Europe over austerity measures that have cut wages, reduced benefits and eliminated many jobs altogether, to rage in Asia over relentlessly low pay, the rising cost of living and hideous working conditions that have left hundreds dead in recent months.

In protests, strikes and other demonstrations held in cities around the planet, activists lashed out at political and business leaders they allege have ignored workers’ voices or enriched themselves at the expense of laborers. In some places, the demonstrations turned violent, with activists clashing with police.

Many nations have been struggling with economic downturns for several years now, and workplace disasters in developing countries are nothing new, but the intensity of some of Wednesday’s gatherings suggested workers’ frustrations have grown especially acute, with many demanding immediate action to address their concerns.

Unions in Greece held a strike that halted ferry and train services, and organized peaceful protest marches through central Athens. The country, which nearly went bankrupt in 2010, is now in its sixth year of a deep recession and is dependent on international bailout loans.

More than 100,000 Spaniards infuriated by austerity measures and economic recession took to the streets of some 80 cities in trade union-organized rallies Wednesday, with the largest protests in Madrid, Barcelona and Bilbao.

Demonstrations in Turkey turned violent when some protesters, angry at a government ban on a symbolic rally point, hurled stones, gasoline bombs and fireworks at riot police.

In New York, thousands of activists armed with flags, puppets and cowbells took to the city’s streets to rally for immigration reform and labor rights.

In a scene reminiscent of Occupy Wall Street’s heyday, protesters marched in downtown Manhattan toward City Hall waving banners and banging on drums.