Clashes broke out in central Athens Friday during a protest outside parliament as lawmakers prepared to vote on austerity measures to deal with Greece's debt crisis.

Protesters chased the ceremonial guard -- dressed in 19th century uniform -- away from the Unknown Soldier's Tomb, threw stones and clashed with riot police, who cleared the area with tear gas and baton charges.

Police with riot shields fired tear gas as demonstrators wearing biker helmets and gas masks pelted them with stones outside parliament in Athens where lawmakers approved the measures.

No injuries or arrests were immediately reported.

The clashes came as about 5,000 demonstrators gathered to protest the euro4.8 billion ($6.5 billion) package that will hike consumer taxes and slash pay for public sector workers by up to 8 percent.

Just before the attack on the two military guards and their escorting officers, during which demonstrators smashed windows and kicked the guard posts, masked youths attacked the head of Greece's largest trade union who was addressing the crowd.

GSEE head Yiannis Panagopoulos traded blows with the rioters before being escorted away.

GSEE and the ADEDY umbrella civil servant union held work stoppages Friday to protest the austerity measures, while hospitals, schools and public transport were closed down.