ROME (JTA) — Erich Priebke celebrated his 100th birthday as protesters scuffled outside his residence with a young man described as a relative of the Nazi war criminal.

Police presence was strong Monday in the neighborhood where Priebke is serving a life sentence under house arrest for his role in the 1944 mass killing of 335 Romans, including some 75 Jews, at the Ardeatine Caves south of Rome.

Scores of protesters gathered outside his building for a sit-in organized by Project Dreyfus, a Facebook group that fights anti-Semitism. Police intervened when some of the protesters started to brawl with the supposed relative, who appeared with a bottle of champagne to toast the former SS captain.

The protesters affixed a banner outside Priebke’s building listing the names of the 335 people killed in the caves.

Meanwhile, posters appeared in several parts of the city congratulating Priebke or attacking the Rome Jewish community’s president, Riccardo Pacifici, who last week called on Italian leaders to make sure that celebrations of Priebke’s birthday did not take place.

One large banner, affixed to a wall near Priebke’s apartment, read “May God curse your accusers, happy birthday Captain Priebke.” It was signed with a swastika and the initials of a neo-Nazi group.

Graffiti reading “Congratulations Priebke” and a swastika were scrawled on the wall of the headquarters of the national partisans’ association.

Last week, authorities said they would bar rumored demonstrations in support of Priebke.