Seven Italian scientists who faced jail for failing to predict a deadly 2009 earthquake have been cleared of manslaughter convictions that had sparked international outrage.

The seven men were sentenced to six years in jail in October 2012 after a court in the medieval town of L'Aquila found them guilty of causing multiple deaths by having negligently downplayed the risk of the town being hit by a major earthquake just days before the killer tremor struck in April 2009.

But after a month-long appeal trial in the mountain town east of Rome, that verdict was on Monday overturned by a panel of three judges which concluded that six of the seven had committed no crime.

The judges partially upheld some of the charges against one defendant, Bernardo De Bernardinis but downgraded his sentence to a two-year suspended prison sentence that will not lead to him having a criminal record.

"The credibility of Italy's entire scientific community has been restored," said Stefano Gresta, the President of the National Institute of Geophysics and Volcanology, whose predecessor, Enzo Boschi, was one of the most eminent of the defendants.

Franco Coppi, one of the lawyers for the scientists, said: "It is very pleasing that our arguments have been upheld although we remain profoundly sorry for the families of the victims and understand their reactions."

But Stefania Pezzopane, an Italian senator and former president of the Aquila region, called the appeal decision "disconcerting and contradictory".

The precise reasons for the verdict will not be made clear until the full written judgment is released in several months' time.

The prosecution may seek to have the convictions reinstated via a final appeal to a higher court.

The defendants had been backed by outraged scientists from across the world.

Numerous critics claimed that their prosecution had put science itself on trial, warning that experts would stop offering any kind of risk assessments if they were opening themselves up to potential litigation.

Many compared the sentencing to the persecution of 17th-century astronomer Galileo, who, under threat of torture, was forced to recant his assertion that the Earth moves around the Sun.