Protesters encircle Greek parliament

People shout during a huge anti-austerity demonstration in Athens' Syntagma (Constitution) square February 12, 2012. Greek lawmakers looked set to endorse a new and deeply unpopular austerity deal on Sunday to secure a multi-billion-euro bailout and avert what Prime Minister Lucas Papademos warned would be "economic chaos. " [Photo/Agencies]

ATHENS - Tension is flaring in Greece as thousands of protesters encircled the parliament Sunday afternoon ahead of a crucial vote after midnight on the new debt deal reached with international lenders last week to avoid a Greek default next month.

A policeman and a photo journalist were slightly injured, according to local media, when protesters clashed with anti-riot police during a mass anti-austerity rally staged by labor unions and Leftist parties.

Demonstrators clash with riot police during an anti-austerity protest in Athens' Syntagma (Constitution) Square February 12, 2012. Greek lawmakers looked set to endorse a new and deeply unpopular austerity deal on Sunday to secure a multi-billion-euro bailout and avert what Prime Minister Lucas Papademos warned would be "economic chaos. " [Photo/Agencies]

According to estimates, some 25,000 people joined the mobilization chanting slogans such as "We say no to the thieves who condemn us to poverty."

Tear gas was used to dispel hooded protesters, who have started pelting rocks and petrol bombs against police forces.

Two women protect protect them from tear gas during a huge anti-austerity demonstration in Athens' Syntagma (Constitution) square February 12, 2012. Greek lawmakers looked set to endorse a new and deeply unpopular austerity deal on Sunday to secure a multi-billion-euro bailout and avert what Prime Minister Lucas Papademos warned would be "economic chaos." [Photo/Agencies]

Some peaceful demonstrators were treated with respiratory problems, Greek media reported. Amongst them were renowned composer Mikis Theodorakis, best known worldwide for the music of the film "Zorbas the Greek" and Manolis Glezos, a Left-wing former MP, who during the World War II tore down the Nazi flag from the Acropolis hill.