AP news said the riots were organized by the comunist party.
http://apnews.myway.com//article/20100506/D9FHH4RO1.html"By ELENA BECATOROS
Demonstrators banging drums and shouting anti-government slogans through bullhorns, unfurled a giant black banner outside parliament earlier Thursday. More than 30,000 demonstrators filled downtown streets, chanting "They declared war. Now fight back."
Prime Minister George Papandreou expelled three Socialist deputies who dissented in the vote, reducing the party's number of seats to 157 in the 300-member parliament.
"We have done what was necessary, not what was easy," Finance Minister George Papaconstantinou said after the vote. "Without these measures, we'd be thrown into the deepest recession this country has ever known."
The bulk of Thursday's protest - organized by the Greek Communist Party - quickly dispersed, leaving about 5,000 demonstrators outside parliament before police pushed them back.
Protester Thodoris Mougiakos said he was angry the IMF would control Greek finances.
"It's blackmail," the 32-year-old engineer said. "There is money, but they spend it on things like armaments and businesses. The church has money too. If we had been drawing money from all these sources, we wouldn't be in this situation now,"