A protest in the central Athenian district of Thiseio held by around 100 people demanding the release from custody of a self-proclaimed anarchist who is being accused of membership to an urban guerrilla group, flared up on Wednesday with minor clashes between protesters and police.
Eleven people were remanded in custody following the scuffles.
Costas Sakkas, 29, has been on hunger strike since June 4 to protest the fact that he has been held in detention for two-and-a-half years, when the maximum the law allows for pretrial custody is 18 months.
Sakkas was arrested in December 2010 but two months before his custody was due to end, he was charged for a different offense and remanded for that.
He is being accused of membership to Conspiracy of the Cells of Fire, charges that he has consistently denied.
Amnesty International on Monday joined calls from leftists groups and political parties for the release of Sakkas, who is under medical observation at Nikaia General Hospital near Piraeus as the hunger strike has taken a toll on his health.
A separate rally in support of Sakkas's release was also organized in Crete.