A man who is suspected of being part of "Sharia4Belgium" leaves the trial of the group in Antwerp September 30, 2014. Reuters/Francois Lenoir

The leader of a Belgian group that's accused of recruiting locals to fight for the Islamic State group has been sentenced to 12 years in jail. The judge of a court in Antwerp reportedly said in his ruling Wednesday that it was clear that Sharia4Belgium was a “terrorist organization.”

Fouad Belkacem, the alleged leader of "Sharia4Belgium," which sent would-be jihadists to the Middle East, was tried alongside 45 others in a case that is the largest of its kind in Belgium, the BBC reported. Prosecutors have accused the group of providing recruits for groups like ISIS, as the European nation remains on high alert following the discovery of a plot in January to kill local police officers across the country. Two shooters were killed in a series of raids in that operation.

"Belkacem's words can only be interpreted as a call to violence and jihad," public prosecutor Ann Fransen argued in the trial, listing a long line of speeches and videos in which the 32-year-old group leader compared military jihad to praying and fasting, Reuters reported.

On Wednesday, only nine of the 46 accused were present in court for the trial. Others are believed to be fighting in Syria or to have died in combat. The judge said that there was insufficient evidence to prove the absent suspects' deaths and so they would be tried as well. The main witness in the trial was 20-year-old Jejoen Bontinck, who became known when his father traveled to Syria to convince Bontinck to return. He has been handed a suspended sentence.

Authorities estimate that about 350 Belgian nationals have left for Syria to fight for groups like ISIS, the highest number per capita in Europe. Around 10 percent of Belgian militants are estimated to have had links to Sharia4Belgium.

Authorities currently estimate there are 3,000 European nationals who have gone to Syria or Iraq to join various Islamic militant groups, Al Arabiya reported. The issue comes at a time when the continent is on high alert following a series of attacks by radical Islamists in and around Paris that killed 17 people.