The Greek Parliament last week passed a new austerity package that bailout creditors had demanded in exchange for paying out more rescue loans. The package raised the retirement age and cut pensions and raised taxes. It has also has eased restrictions on firing workers.
In a chaotic scene on Thursday, riot police chased protesters through the exhibition complex from building to building. There were no immediate reports of arrests.
Left-wing German lawmaker Annette Groth joined the protesters outside the conference center, where clashes with riot police also occurred.
"I have also been unemployed," she told the crowd. "It is not you who should pay the price for this crisis but the rich."
That argument resonates with many Greeks, who feel that low income earners have borne the main brunt of the country's brutal austerity program.
The recent revelation that Greek tax officials took no action to investigate lists of people with accounts in Switzerland — provided by French authorities — provoked outrage.
On Thursday, Finance Minister Yannis Stournaras formally asked Britain to forward information on Greek nationals with offshore HSBC accounts on the Isle of Jersey. The move followed a request from Greek prosecutors, after a list of more than 4,000 alleged HSBC customers with accounts on the offshore financial center was leaked to British authorities.