Italy's Jews and relatives of victims of the country's worst wartime atrocity are furious with authorities for allowing a demonstration to press for the release of jailed former Nazi SS captain Erich Priebke.

Anger over the demonstration, planned for tomorrow in Rome, has intensified because a parliamentarian of Prime Minister Silvio Berlusconi's party plans to attend.

Mr Priebke, 90, is serving a life sentence for his role in the murder of 335 civilians in Rome in 1944. He was extradited from Argentina in 1994 and convicted in 1998.

"This is an outrage, an offence to the dead," said Oreste Bisazza Terracini, who represented Rome's Jewish community at the military trials that led to Priebke's conviction.

"Since he was free for 50 years in Argentina after the war, I think it's only right that he spends at least the last part of his life in detention," he told Reuters.

Priebke, who has said he was just following orders, was convicted for his role in the Ardeatine Caves Massacre in which Nazi occupiers of Rome killed 335 men and boys, 75 of them Jews, in caves outside the city on March 24, 1944.

Hitler had ordered the massacre in reprisal for the killing of 33 German soldiers by Italian partisans. Mr Priebke was responsible for ticking off the names of victims on a list as they arrived at the caves. He admitted to killing two himself.

"Priebke is an old man who is not dangerous to society. He is sick and should be able to go home to Argentina to die," said Paolo Giachini, president of the organisers of the demonstration, the Association of Man and Liberty.

The decision to allow the pro-Priebke demonstration has sparked a tug of war between Italian institutions.

Rome's prefect authorised the demonstration but later Rome mayor Walter Veltroni, a member of Italy's largest leftist party, refused to let the demonstrators erect a podium or use city electricity. Mr Giachini said they would bring generators.