Government spokesperson Aristotelia Peloni on Wednesday described the incidents that occurred in the Athens district of Nea Smyrni on Tuesday night as "sad and divisive".
Strong police forces with riot control forces (MAT) have lined up at the site of the 37th GSEE (General Confederation of Labour) Congress in Kavouri.
Thirty-three people were arrested and 53 were detained during protests in the Athens district of Exarchia late on Sunday night, the anniversary of the November 17, 1973 student uprising at the Athens Polytechnic.