(This July 15 story corrects to remove reference in 2nd paragraph to Italians fighting with Russian-backed separatists)

ROME (Reuters) - Italian police have seized a large arsenal of weapons, including an air-to-air missile, in raids on neo-Nazi sympathizers, they said on Monday.

Elite police forces searched properties across northern Italy following an investigation into Italians who had fought in eastern Ukraine in the conflict between government forces and Russian-backed separatists, a police statement said. A police official declined to say who they had been fighting for.

Three men were arrested, including a customs officer who has previously stood for parliament for an extreme right party.

During their raids, police discovered a French-made Matra air-to-air missile that appeared to have once belonged to the Qatar armed forces. Subsequent checks showed the weapon was in working condition but lacked an explosive charge.

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Police said the suspects had tried to sell the missile in conversations with contacts on the WhatsApp messaging network.

Among other weapons uncovered were 26 guns, 20 bayonets, 306 gun parts, including silencers and rifle scopes, and more than 800 bullets of various calibers. The arms were primarily from Austria, Germany and the United States.

Police also seized Nazi memorabilia from the properties.

“The police investigation ... came into being because of the activities of some Italian fighters with extremist backgrounds who had taken part in the armed conflict in the Ukrainian region of Donbass,” the police statement said.

More than 10,000 people have been killed since 2014 in fighting between pro-Russian separatists and Ukrainian forces in eastern Ukraine.