A Brussels judge on Monday sent over a dozen people to trial on charges of aiding and abetting terrorists, including those suspected in last year's Madrid train bombings.
An autumn trial would be the first test for a 2004 law making it a crime to consort with terrorists.
Prosecutors accused 13 defendants of membership in the Groupe Islamique Combattant Marocain, an anti-Western group formed by veterans of the 1980s Afghan war against the Soviet Union.
In addition to linking the GICM to the Madrid blasts, they alleged the group's members had a hand in the May 16, 2003 bombings in Casablanca that killed nearly 50 people.
Four other defendants were named in court but they are in foreign jails, including three in Spain linked with the Madrid trains attacks that killed 191 people and wounded more than 1,500 on March 11, 2004.
At least three defendants of the 13 suspects were born and raised in Maaseik, a town of 24,000 on Belgium's eastern border with the Netherlands. One, Khalid Bouloudo, 30, is alleged to be the Belgian coordinator of the GICM.
His lawyer, Katelijne van Bellinghen, said there were "serious question marks" about her client's alleged membership in a terrorist organization.
"Until now, we have seen no concrete elements in the prosecution's case that would clearly prove any sort of membership (in a terrorist group) by any defendant, or if they in any way aided and abetted such an organization," she told the VRT television network.
Another suspect, Abdelkader Hakimi, is linked to the Madrid attacks.
The defendants also include Mourad Chabarou who prosecutors say sheltered a suspected terrorist in the Madrid attacks. Police say his Brussels apartment contained fingerprints belonging to Mohammed Afalah, one of the suspects in the Madrid bombings.
In Maaseik, Bouloudo and his Muslim friends were known to Mayor Jan Creemers.
Creemers told the AP, that a few years ago, six Muslim women in his town suddenly showed up in public completely covered in bhurkas.
"I didn't understand that," Creemers said.
"Born and raised here! That scared many people" in Maaseik, whose Muslim population totals under 800, Creemers said.
His town council passed a bylaw last year prohibiting anyone from being completely covered in public or face a Ђ125 (US$153) fine. Five women have since shed the bhurka, but Bouloudo's wife was recently fined for wearing a bhurka in public.
Prosecutors said all GICM suspects take their cue from extreme fundamentalist Islamic teachings, including that preached by Abu Qatada, the radical preacher Britain seeks to expel.
Last year, a Dutch court extradited Bouloudo - who worked as a pastry baker in the Netherlands - to Belgium.
At a Dutch court last year, he denied involvement in terrorist activities. By then, Belgian police had arrested 15 other terrorist suspects in Maaseik, Brussels and other Belgian cities.