France's Interior Minister Gerald Darmanin and the Paris police force faced criticism and questions on Monday over why a march of about 600 neo-Nazis through the streets of the capital was authorised at the weekend.
Hundreds of men dressed in black from far-right groups marched with flags and chanted slogans through the upmarket Left Bank district of Paris to commemorate the death of a far-right activist, Sebastien Deyzieu, in 1994.
The city authorised the protest and police patrolled near by.
Socialist Party senator David Assouline called on Mr Darmanin to "explain yourself".
"It's unacceptable to have allowed 500 neo-Nazis and fascists to parade in the heart of Paris," Mr Assouline wrote on Twitter.
"Their organisations, the display of their ideology, slogans, insignias, are as much an insult to the dead as an incitement to racial hatred."
France marked its traditional May 8 public holiday on Monday to commemorate the victory of Allied forces over Nazi Germany in 1945, and the lives lost in the fight against fascism.
Ian Brossat, a spokesman for the Communist party, joked that "saucepans are clearly more dangerous than jackboots".
Left-wing charity Attac also wrote that the far-right "demonstrates their hatred with complete impunity in the centre of Paris while the state is seeking to outlaw saucepan-banging".
Well-known intellectual Jacques Attali called the rally "intolerable."
Protests in France - in pictures
The Paris police department reacted on Monday by explaining that it did not have the legal powers to prevent a demonstration unless there was a "proven risk to public order".
"Given that this demonstration had not caused any problems or public order issues during previous years, the Paris prefect was not in a position to take steps to ban it," it said.
It referred to a previous attempt in January to stop a flaming-torch rally by the far-right "Paris Pride" group, which was overturned by a judge after an appeal by organisers.
Protests were banned on Monday around the Champs-Elysees in Paris where French President Emmanuel Macron attended a May 8 ceremony at the Arc de Triomphe war memorial.
Police in eastern Lyon also outlawed demonstrations Monday near a war memorial where Mr Macron was expected to pay tribute to French Resistance hero Jean Moulin.
An appeal from the CGT trade union was rejected by a local court.
French pension protesters block Louvre in Paris - video
Members of the government have been pursued by saucepan-banging protesters since Mr Macron signed a deeply unpopular pension reform into law on April 15 that will raise the retirement age to 64 from 62.
The far-right demonstration in Paris on Saturday ended with participants chanting "Europe, youth, revolution", the slogan of the violent GUD far-right student group that was influential in the 1990s, AFP reported.
Two former GUD members, Axel Loustau and Olivier Duguet, who have worked closely with French far-right political leader Marine Le Pen, were photographed at Saturday's rally, the Mediapart website reported on Monday.
The Interior Ministry has banned some extremist anti-immigration groups in recent years, including Generation Identitaire and Zouaves Paris.