Protesters assaulted an ex-minister and clashed with riot police in Athens as thousands joined street demonstrations during a general strike to protest new austerity measures by the debt-hit government.

Hours after parliament approved another batch of wage cuts, this time in the country’s inefficient public utilities, the centre of the Greek capital was left scarred with debris and the heavy smell of tear gas and smoke.

For over an hour, riot police chased and clashed with hooded and helmeted protesters who set fire to garbage bins and cars, threw firebombs and chunks of broken masonry and vandalised bus shelters and shops.

The police retaliated with tear gas and flash grenades that split apart a demonstration of at least 20,000 people called by Greece’s two main unions under a general strike, the seventh this year, against the Socialist government’s austerity drive.

As the demonstration moved towards the Greek parliament, a group of protesters chased down and assaulted a former conservative minister and lawmaker who had just left the building, according to an AFP photographer.

Photo footage showed former transport minister Costis Hatzidakis bleeding from the top of his head and nose after being cornered outside a department store by around a dozen people, some of whom were punching him.

Another 20,000 people joined a protest in the northern city of Thessaloniki earlier in the day that also resulted in violence when youths hurled firebombs at a central government building and vandalised several banks and stores.

In Brussels, hundreds of protesters formed a human chain around the European Commission’s glass building to denounce the belt-tightening launched by governments around Europe.