Greek authorities have charged four men over a weekend mob attack on the 75-year-old mayor of the country's second-largest city, carried out in an apparent venting of nationalist sentiment.

The suspects, aged between 17 and 36, were formally accused of grievous bodily harm and breach of the peace over Saturday's attack on Yiannis Boutaris.

The mayor of Thessaloniki required hospital treatment after being thrown to the ground, kicked and punched by about 12 people during a ceremony honoring Greek victims of mass killings by Turks during World War I.

The three adults were to be tried later Monday, while the 17-year-old will appear before a court for minors.

One of the suspects allegedly told police he was angry at a recent statement by Boutaris, a liberal centrist, favoring friendlier relations with Turkey.