In a 12-minute clip, young people were secretly filmed making fascist gestures. In one scene which appeared to be filmed at a mountain retreat, young members are seen yelling “Sieg Heil, Sieg Heil. We are really fascists”.

Political opponents demanded a response from Ms Meloni as she was concluding the G7 summit in Puglia, but she has yet to comment.

Her opponents decried it as proof the political Right is still haunted by its fascist past.

“The Right can whitewash itself but it cannot hide anti-Semitism and racism,” Elly Schlein, head of the main opposition Democratic Party (PD) told the La7 TV channel.

The PD, the Five Star Movement and the Green-Left Alliance demanded an explanation in Parliament for what they termed the ‘’incomprehensible silence’’ from the prime minister and her government over the investigation.

Ms Schlein said the prime minister could not deny there was fascism within her own party.

She pointed to Ignazio La Russa, the president of the Senate, who has openly admitted having a bust of Benito Mussolini in his home.

Left-wing MP, Nicola Fratoianni, echoed her concern. “The youth movement of the prime minister’s party feeds on fascist and Nazi ideological rubbish, which praises the Duce and shouts ‘Sieg Heil’,” he said.

‘Dedicated militants’

But Italo Bocchino, a former Right-wing MP and journalist, dismissed the controversial news report as “garbage” and described the National Youth as a community of committed and dedicated militants which made an important contribution to democracy.

Ms Meloni once described Mussolini as “a good politician” and it is not the first time the Italian prime minister has been asked to distance herself from blatant displays of fascist behaviour.

Italian opposition parties demanded the dissolution of extreme-Right parties in January this year after a video was released showing hundreds of black-clad men making fascist salutes at a rally in Rome.

The gathering was held in front of the former headquarters of the Italian Social Movement (MSI) a neo-fascist party that eventually morphed into the conservative Brothers of Italy, co-founded by Ms Meloni.

It took place on Jan 7 to mark the 46th anniversary of the Acca Larentia massacre, when three young neo-fascist militants from the MSI were killed.

Italy’s post-war constitution forbids the reorganisation of Mussolini’s dissolved Fascist party, but extreme Right groups have been able to give their parties new names and claim to be new entities.