Tens of thousands of Greek workers struck and marched to protest demands by the country's international lenders that Athens impose more austerity measures before they will agree to hand Greece another segment of a bailout to keep the government afloat.

Most of the protest was peaceful, but police fired tear gas and stun grenades at the youths after their assault. One man in his mid-60s died of a heart attack during the demonstration.

The country's second general strike in a month was timed as a protest against European Union leaders as they gathered in Brussels for a two-day summit, to discuss new ways to resolve the three-year debt crisis in the 17-nation euro currency bloc.   

Greek union leader Kostas Tsikrikas said his countrymen cannot withstand more austerity measures.

"We are sending a strong message to Europe, to the council summit, that  the people cannot take any more of this harsh and one-sided austerity," he said. "We will coordinate our efforts with all the unions of Europe in order to change this policy on a national and European level."

Greece and its outside lenders have been negotiating for weeks over terms of a $17 billion austerity plan, but have yet to reach agreement. Greece says it will run out of money next month and not be able to meet its financial obligations.

EU leaders are faced with resolving funding for Greece even as Spain decides whether to seek a bailout, or a line of credit, to solve its debt woes. The eurozone nations are looking to tighten spending and banking controls by the end of the year, but are unlikely to decide major issues at this week's summit.