A radical Islamic group that recruited youngsters to fight in Syria was a terrorist organization that wanted to violently overthrow democracy and replace it with strict sharia law, a Belgian court ruled Wednesday in a case that played out against a backdrop of soaring terror fears.

The court in Antwerp sentenced the Sharia4Belgium group's "charismatic leader," Fouad Belkacem, to 12 years' imprisonment and gave dozens of other members lower sentences. Belkacem, who was led into court in handcuffs by police in body armor, smiled as he listened to the judgment.

The verdicts came in one of Belgium's biggest ever terror trials -- 46 Muslims were originally indicted, though only a handful appeared in court. Others are believed to be fighting with Sunni armed groups in Syria or to have died in its civil war.

Clamping down on the Sharia4Belgium network, which was disbanded more than two years ago, appears to have done little to rein in Islamic extremists in the country.

Police have carried out a string of raids and arrests this year since a firefight with suspected Islamic terrorists in the eastern industrial town of Verviers shortly after the Paris terror attacks last month.

Belgian police said the Verviers operation, which left two suspected extremists dead, foiled an imminent terror attack. In the aftermath of the Verviers raid, paratroopers were sent onto the streets to help police maintain security and Belgium increased its terror-threat warning to the second-highest level.

Dimitri Bontinck, the father of one of those convicted, said he was happy that his son, Jejoen Bontinck, received only a suspended sentence after he agreed to testify against the group.

But he warned the trial could only fuel unrest.

"This verdict could create more hate and frustration," Bontinck said.