Three environmental activists with links to European anarchist groups were found guilty Friday of plotting a bomb attack on an unfinished IBM nanotech research facility near the Swiss city of Zurich.

Switzerland's highest criminal court declared 35-year-old Costantino Alfonso Ragusa, his 29-year-old wife Silvia Ragusa Guerini and their 26-year-old Swiss friend Luca "Billy" Cristos Bernasconi guilty of conspiring last year to destroy the research center as it neared completion.

The trial drew attention to a loose-knit network of European anarchists, with prosecutors linking the trio to extremist environmental and animal-rights movements that have claimed responsibility for several violent attacks in the U.S. and Europe since the 1990s.

During the trial, federal prosecutor Hansjoerg Stadler described the defendants as having close links to the Earth Liberation Front, ELF, and Animal Liberation Front, ALF. He said Ragusa and Guerini are known as founders and members of the Italian movement "Terra selvaggia," or Wilderness, which has connections to ELF, and that Bernasconi is an Italian member of ALF.

In March, a letter bomb sent to an office of the Swiss nuclear power industry contained a note demanding the release of Ragusa, Guerini and Bernasconi. Two people were injured in the attack, which Swiss prosecutors said was claimed by the Italy-based Informal Anarchist Federation, or FAI.

The three were arrested in April 2010, about two miles (3 kilometers) from the IBM facility. Their defense lawyers called it a bogus traffic stop that showed police had improperly presumed they were guilty. But at trial the prosecution said police found in their possession an explosive gel and a mixture of fuels that, when combined, would detonate with almost as much power as TNT.

The presiding judge at the trial, Walter Wuethrich, said the three were found guilty of illegally hiding and transporting explosives, and of plotting an incendiary attack on the IBM center. They were acquitted of importing explosives into Switzerland. The trio were not charged with an attempted bombing, because their plot was foiled by police ahead of time.

The Italian couple, Ragusa and Guerini, and Bernasconi, a Swiss citizen living in Italy, were handed prison sentences ranging from 3 years and 4 months to 3 years and 8 months. This was slightly higher than federal prosecutors had recommended.

They each have the right to deduct 464 days from those sentences for time already served since their arrests. The court said they would be held under special security conditions because all three had demonstrated "a serious risk of evasion and flight to Italy."

Defense lawyers declined to comment but Stadler, the federal prosecutor, said he was pleased with the sentence.

"Very serious crimes are now being punished and, thanks to the good job done by the police, damages were prevented," he said.

Security was extraordinarily tight for their two-day trial this week at the Federal Criminal Court in the southern Swiss city of Bellinzona, where about 50 supporters of the defendants gathered with signs and loudspeakers outside the courthouse.

AP