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 across 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.

The anger was painfully evident in Bangladesh, where the collapse last week of an illegally built eight-story facility housing multiple garment factories killed more than 400 in a Dhaka suburb. The building collapse followed a garment factory fire in November that killed 112 people in the country, and it has increased the pressure on the global garment industry to improve working conditions.

A loud procession of thousands of workers wound through central Dhaka on Wednesday. Many waved the national flag and demanded the death penalty for the now-detained owner of the doomed building. From a loudspeaker on the back of a truck, a participant spoke for the throngs gathered: "My brother has died. My sister has died. Their blood will not be valueless."

The Bangladesh tragedy drew a denunciation from Pope Francis during a private Mass at the Vatican. He blasted what he called the "slave" wages of those who died, many of whom were being buried Wednesday as other bodies were still being pulled from the rubble. Francis criticized the focus on "balance books" and personal profit that he said is tied to the failure to pay workers fair wages.

In Greece and Spain, increasing numbers of people are losing their jobs as governments grappling with a debt crisis have been cutting spending, raising taxes and pursuing other stinging austerity measures.

Unions in Greece held a May Day strike that brought ferry and train services to a halt, and organized peaceful protest marches through central Athens.

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. Francisco Moreno, 47, an unemployed bookkeeper, scoffed at Spanish leaders' calls on the public to be patient. "You can only be patient if you have savings, money in the bank," he said. "You can't be patient if you have no income and kids to feed."

In Mexico, public school teachers who have blocked highways and battled police in recent months marched peacefully Wednesday in Mexico City and the southern city of Chilpancingo, hoping to block an education reform law that introduces teacher evaluations and diminishes the power of unions in hiring decisions.

In his May 1 speech, President Enrique Peña Nieto promised a new effort to produce more salaried jobs, noting that two-thirds of Mexicans have no benefits and low wages.

Turkey turned violent when some demonstrators, angered at a government ban on a symbolic rally point, hurled stones, gasoline bombs and fireworks at riot police. Security forces used water cannons and tear gas to prevent crowds from accessing Taksim Square, which is undergoing a face-lift, and 22 police officers and at least three passers-by were injured. More than 70 people were arrested.

Boos and whistles from protesters forced Danish Prime Minister Thorning-Schmidt to halt her May Day speech to thousands in Aarhus, northwest of Copenhagen. As she was walking to her car, a man squirted her with a water pistol. Police detained the 23-year-old man; the premier was not injured.

Swedish police said seven people were arrested and five were injured as counterdemonstrators tried to interrupt a May Day parade by right-wing extremists in the southern city of Jonkoping. Sixty others were briefly detained as officers tried to keep the two sides apart.

In Indonesia, the world's fourth-most-populous country, tens of thousands of workers rallied for higher pay and other demands.

In the Philippines, an estimated 8,000 workers marched in Manila to also demand better pay and regular jobs instead of contractual work. Some rallied outside the U.S. Embassy, torching a wooden painting stamped with the words "low wages" and "union busting" that depicted Philippine President Benigno Aquino III as a lackey of President Obama.

More than 10,000 Taiwanese protested a government plan to cut pension payouts to solve worsening fiscal problems.

In Cambodia, more than 5,000 garment workers marched in Phnom Penh, demanding better working conditions and a salary increase from $80 to $150 a month. About a half million people work in the country's $4.6 billion garment industry, which makes brand-name clothes for many U.S. and European retailers.

And in Havana, tens of thousands of Cubans joined the communist nation's traditional May Day march in the Plaza of the Revolution. This year's edition was dedicated to Cuba's ally, the late Venezuelan President Hugo Chavez. Cuban President Raúl Castro attended the event but did not speak.