Protesters have broken into a conference center and clashed with police in northern Greece after gathering to demonstrate against the presence of a German government official.

The protesting municipal workers pushed and threw coffee on a German diplomat who arrived to attend the conference of Greek and German mayors being held in the city of Thessaloniki. They later forced open shutters and entered the conference center, where they clashed with riot police.

A German deputy labor minister who has been appointed special envoy to Greece, Hans-Joachim Fuchtel, was also attending the event.

Protest groups in Greece often blame Germany for harsh austerity measures imposed by rescue lenders. Greece is about to enter a sixth year of recession while unemployment has risen to 25 percent.

• Thessaloniki