MILAN (Reuters) -An Italian judge on Tuesday sentenced 16 Inter and AC Milan hardline 'ultra' soccer fans to prison terms ranging from two to 10 years for crimes including murder, extortion and criminal association with links to the 'Ndrangheta mafia.

The verdicts followed a fast-track trial held behind closed doors in a high security court attached to Milan's San Vittore prison. The case resulted from the arrest of 19 people last September following an investigation by Milan prosecutors and the office of the national anti-mafia prosecutor.

A second trial, which involves three other AC Milan ultras, will deliver its verdict on June 19.

Prosecutors argued that the ultra groups acted as "private militias" with criminal influence far beyond the stadium, alleging infiltration by both the mafia and far-right extremist groups. 

Around 200 AC Milan fans demonstrated outside the court in solidarity with their fellow ultras before the verdicts were handed down.

Judge Rossana Mongiardo sentenced Andrea Beretta, former leader of Inter Milan's ultras, to 10 years in prison. He had confessed to the murder in September of Antonio Bellocco, a leading figure in the 'Ndrangheta and a fellow Inter ultra. 

After his arrest, Beretta became a state witness and cooperated with investigators, contributing to a lower sentence than might otherwise be applied in a murder case.

Luca Lucci, the historic leader of AC Milan's ultras, who is also under investigation in a parallel case for international drug trafficking, was sentenced to 10 years in prison plus four years of probation on charges of criminal association and attempted murder.

At the end of the trial, the defence lawyers had dismissed the prosecution's charges as "a house of cards".

In a fast-track trial, cases are heard by a judge behind closed doors without witnesses. Defendants get their sentences reduced by a third if they agree to the process.

The judge also ordered an immediately enforceable provision of 50,000 euros ($58,000) each payable to Inter and Milan, plus an additional 20,000 euros to Italy's Serie A soccer league. Any further damages will be assessed separately in civil proceedings.

Leaders of the ultras, together with the 'Ndrangheta mafia, ran ticket scams and protection rackets on drink stands and car parks around the city's San Siro stadium, which both clubs share, prosecutors said.

According to investigators, the case discovered in Milan is not the only one in Italy where crime bosses and the far-right are tapping into the muscle and money-spinning activities of hardline 'ultra' soccer fans.

Similar issues have been uncovered in Greece where police have made dozens of arrests as they investigate the alleged links between violent sports fans and criminal gangs.  

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(Reporting by Emilio ParodiEditing by Keith Weir)