Police arrested three people, including Fabio Del Bergiolo, 50, a former candidate for the neo-fascist Forza Nuova party, whose home was found to contain a huge stash of arms as well as neo-Nazi propaganda and Hitler memorabilia.

"During the operation, an air-to-air missile in perfect working order and used by the Qatari army was seized," police said of the 800 kilogramme Matra missile.

They also found automatic assault rifles that they described as "latest generation" among the cache.

"This is a significant seizure, with few precedents in Italy," said Turin police commissioner Giuseppe De Matteis.

The missile, 3.54 metres (more than 11 feet) long was made in France and Del Bergiolo had been hoping to sell it for 470,000 euros ($529,000), according to Italian media reports.

The missile was "without explosive charge, but re-armable by people specialised in the field," police said.

"For now, nothing leads us to suspect" an active plot to use the weapons, said counter-terrorism official Eugenio Spina.

The other arrests were a Swiss, 42, and an Italian, 51, accused of holding and marketing the missile, which was found by police at a warehouse near the small Rivanazzano Terme airport in the Pavia province.

- 'Extremely dangerous' -

The Mantra Super 530 F was a modernisation of the R530 missile that went into service in 1980, and has a range of 25 kilometres (15 miles), with an explosive charge of 30 kilos.

"It is extremely dangerous and risky to turn it into a missile to fire from the ground, unless you have good engineers and equipment," a missile expert who asked not to be named told AFP.

Similarly, because of its age, it is "extremely unlikely that it can be used, but its use can be changed," he added.

The raids were the result of a police probe into Italian extremists known to have joined pro-Russian rebels fighting in Ukrainian.

Messages intercepted by the police led them to investigate Del Bergiolo, who had sent photographs of the missile for sale through the Whatsapp messaging service.

They put him under surveillance before raiding his home and finding a stash of weapons including a Scorpion machine gun, 306 firearm parts and 20 bayonets.

His collection included street signs from the Nazi era, including one reading "Adolf-Hitler Platz".

- Trafficking war weapons -

Police in Pavia also found the cockpit of a military plane.

The Digos law enforcement agency, which deals largely with terrorism and organised crime, led the operation from Turin with assistance from police in Forli, Milan, Novara and Varese.

"We have some idea about what the seized equipment could be used for, but will not speculate," De Matteis told reporters.

The Forza Nuova party released a statement Monday distancing itself from Del Bergiolo.

Police have carried out several raids in recent weeks on far-right targets around Turin, with a man arrested earlier this month for advocating fascism and possessing illegal weapons.

While Italy's far-right interior minister Matteo Salvini was uncharacteristically quiet following the raid, the opposition centre-left Democratic Party (PD) urged the country's populist government to do more to tackle right-wing extremists.

"The far right in this country trafficks weapons of war, and even missiles. It's an incredible, very serious event," said Maurizio Martina, the PD's former party head.