Demonstrators clashed with the riot police in the center of Athens following a huge rally in Syntagma Square against the use of the term Macedonia by FYROM.
According to reports, police used tear gas to push back the demonstrators, many of whom were wearing bike helmets and were holding Greek flags.
Greek media speculate that they were members of the extreme-right Golden Dawn whose leaders were also at the rally.
Earlier, a counter-demonstration by leftist groups was held at Propylaia, less than a mile away from the main event.
