THESSALONIKI, Greece (AP) — Anarchists and riot police have clashed in Greece after some 2,000 protesters from across the Balkans marched in the northern city of Thessaloniki against nationalism.

Police used tear gas and threw stun grenades at the anarchists, who also barricaded themselves at the University of Thessaloniki. Police are prohibited by law from entering the campus to make arrests.

The gathering of Balkan anarchists was organized after far-right activists burned down an anarchist collective's premises during a January rally protesting the use of the name Macedonia by Greece's northern neighbor.

Nationalist tensions remain pervasive in the Balkans, and Greece and neighboring Macedonia have seen recent protests over a decades-long name dispute. Greece argues that Macedonia's name in its current form implies a territorial claim against its own region with the same name.