ISTANBUL, Turkey - Workers around the world united in anger during May Day rallies Wednesday - from fury in Europe over years of 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 alone.

In protests, parades, 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 during what has been a difficult few years for the global economy. In some places, the demonstrations turned violent, with activists clashing with police.

The pain was especially fresh 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 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 as he addressed worshipers at 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 are 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. Both countries have unemployment rates hovering just above 27 percent.

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. The country, which nearly went bankrupt in 2010, is now in its sixth year of a deep recession and is dependent on international loans.

While the austerity drive has succeeded in reducing high budget deficits, it has been at a huge cost: Under the terms of its latest loan disbursement, Athens has agreed to sack about 15,000 civil servants through 2014.

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