ATHENS: Police in Athens on Tuesday fired tear gas to disperse protesters who tried to storm a steel barricade near parliament as German Chancellor Angela Merkel held meetings with Greek leaders a few blocks away.

Small gangs of masked youths threw bottles and pieces of broken masonry at riot police and tried to smash store windows as police chased them down, AFP reporters witnessed.

Some 25,000 protesters have massed in the capital to protest against the visit of Merkel, the leader of Europe's strongest economy who is seen as an instigator of tough austerity policies imposed on the recession-hit country since 2010.

Some demonstrators were brandishing banners reading "You are not welcome, Imperialisten Raus" (Imperialists out)" or "No to the Fourth Reich", while two Nazi flags were draped on the steel fence near parliament and set on fire.

Over 45 people had earlier been detained by police for questioning around Athens ahead of the demonstrations, including a man who tried to approach the German embassy with a protest banner, police said.

Two men were also arrested.

According to the state-run Athens News Agency, one of them is a suspected member of the radical anarchist group Conspiracy of Fire Nuclei, which last year sent a wave of parcel bombs to foreign missions in Athens and a trio of European leaders -- including Merkel -- abroad.