The tragedy in the Tuscan port of Viareggio was Italy's deadliest rail accident in over 30 years and remains the country's worst of the 21st Century.

The executives were held responsible for poor infrastructure and risk-avoidance systems deemed to have contributed to a freight train carrying liquid petroleum gas derailing and exploding.

The full extent of their liability and the judges' assessment of where exactly the blame lies will not be known until a written verdict is published at a later date.

Moretti, one of Italy's most prominent industrialists and the current boss of defence and engineering giant Leonardo, was found guilty of manslaughter and causing multiple injuries and was sentenced to seven years in prison.

But, like the others convicted, he will not serve any of it before at least the first of two possible appeals have been heard.

That could take years and there is a strong chance the charges could time out before a definitive conviction can be obtained.

Moretti was one of 33 people charged with manslaughter, causing a disaster and other charges in connection with the derailment and explosion of a freight train carrying liquid petroleum gas through the Tuscan coastal town of Viareggio on June 29th, 2009.

The force of the blast brought down two small blocks of flats, where many of the victims lived.

Relatives of the casualties briefly applauded after the verdicts were pronounced in court, where empty chairs were adorned by T-shirts printed with images of each of the dead.

“We are still the ones who have had the heaviest sentences,” said Claudio Menichetti, whose daughter Emanuela, 21, died from burns 42 days after the disaster.

“We have already been given a life sentence,” he told La Repubblica.

Neither Moretti or Michele Mario Elia, another top railways executive who was given a seven years, six months sentence, were in court to hear the verdicts.

Prosecutors had requested 16 years for Moretti and 15 for Elia. Not all charges against them were upheld.

The court did not issue an explanation for its ten acquittals.

Moretti, 63, has been in charge of Leonardo since May 2014. He was Italian State Railways (FS) boss from 2006-14.

Leonardo's board of directors late Tuesday unanimously confirmed “its full confidence” in Moretti.

He would retain his “full capacity” to carry out his functions, the board said in a statement.

The court proceedings and Moretti's conviction hit Leonardo shares which closed down 2.3 percent in Milan. The company, formerly called Finmeccanica, is best known for its helicopter production.

The Viareggio tragedy was the worst rail accident in Italy since two high-speed trains collided south of Bologna in April 1978, leaving 50 people dead.

Another collision, in the southern region of Puglia in July of last year, left 23 dead.

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