Scientists warned that researchers in areas involving unpredictable natural threats, like volcanology and even meteorology, will now be more reluctant to offer advice and insight to the public.

"If it stands, this verdict will have a chilling effect on earthquake science in Italy and throughout Europe," said Sandy Steacy, professor of earthquake physics at the University of Ulster.

"Who would now be willing to serve on an earthquake hazard evaluation panel when getting it wrong could mean a conviction for manslaughter?"

The ruling comes at a time when scientists are being coaxed into more active engagement with the public to demonstrate the importance of their work for the economy and the community.

"This case suggests that such engagement can be very dangerous," said Steacy.

Prosecutors had argued the experts gave inaccurate reassurances after tremors that preceded the 6.3 magnitude quake.

The six seismologists and one government official took part in a meeting before the quake in March 2009 where a risk assessment committee told city officials that a major quake was improbable, although not impossible.

"What those six scientists said was correct and any seismologists would support it," said Roger Musson at the British Geological Survey. "It seems to be wrong that they should be prosecuted for offering scientific advice to the best of their ability."

In the United States, Michael Halpern at the Union of Concerned Scientists lobby group said in a blog: "This is an absurd and dangerous decision that U.S. officials should rebuke, and Italian President Giorgio Napolitano should overturn."

Scientists warned the ruling could have repercussions beyond Italian borders and across other disciplines.

"This bizarre verdict will chill anyone who gives scientific advice, and I hope they are freed on appeal," said David Spiegelhalter, a professor for the public understanding of risk at Cambridge University.

"The lesson for me is that scientific advisors must try and retain control over how their work is communicated, and are properly trained to engage with the public."

In the last week, a broad coalition of British biomedical research groups, from universities to drug companies, signed a pledge to be more open and engage with the public to bolster support for animal experimentation. That coincided with a new Ipsos Mori poll showing a slight fall in backing from the public for the scientific use of animals.

At the time, Sir Mark Walport, director of the Wellcome Trust medical research charity, blamed the decline on the reluctance of scientists to speak out after high profile cases of intimidation by sometimes violent animal rights activists.

Some scientists said the advice on the L'Aquila quake could have been communicated more clearly, with more emphasis placed on the small possibility of a major quake, but there was a chorus of condemnation for the verdict.

"Imagine if the government brought criminal charges against your local meteorologist for not being able to predict the exact path of a tornado," said Halpern. "Scientists need to be able to share what they know - and admit what they do not know — without the fear of being held criminally responsible should their predictions not hold up".

(Additional reporting by Deborah Zabarenko in Washington; Editing by Jon Hemming)

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