Greek police in Athens fired tear gas to break up protesters at anti-austerity demonstrations on Wednesday. Some protesters in the crowd of some 12,000 people threw rocks and firecrackers at police.

The street protests were part of a 24-hour general strike by Greek workers over a new round of austerity measures insisted upon by the heavily indebted country's creditors. Travel was disrupted and hospitals were working with emergency staff only as the labor unions decried cuts to salaries and pensions.

More than 150 flights were grounded in the middle of the day as air-traffic controllers joined in the strike for four hours.

The austerity measures are part of an agreement made between the left-wing government of Prime Minister Alexis Tsipras and the country's creditors, mainly the European Central Bank (ECB) and the International Monetary Fund (IMF), to receive badly needed cash in order to avoid bankruptcy.

Some protesters signs read, "No to the new looting of salaries and pensions"

"We want to send a decisive message to the government, the European Union and the International Monetary Fund that we will not let them cut up our lives," Alekos Perrakis, a senior member of Communist union PAME, told reporters.

The regulations are set to be voted on in parliament on Thursday.

Merkel, Tspiras talk debt relief

While many Greeks have swallowed the bitter pills of previous austerity measures, what incensed the striking workers on Wednesday was news that many of the cost-cutting rules will be extended beyond the terms of the country's most recent rescue package. In their eyes, this was tantamount to a fourth bailout without receiving any new funds to help the struggling economy.

"No to the new looting of salaries and pensions," the civil servants' union ADEDY said in a statement.

On top of the general strike, mariners were in the midst of a four-day walkout, shutting down ferry services between Greece's many islands and the mainland.

Also on Wednesday, Tsipras spoke via telephone with German Chancellor Angela Merkel to discuss the Athens' financial situation. According to Tspiras' cabinet, the two leaders agreed that an upcoming meeting of the Eurogroup, the countries that use the common euro currency, on May 22 would be dedicated to resolving Greece's debt crisis.

es/sms (AP, AFP, dpa, Reuters)