Brussels - The trial of 19 Belgians on terrorism charges began on Monday under tight security amid concerns the 15 men and 4 women were part of a local jihadist recruitment network.
They face charges of either fighting alongside jihadist groups in Somalia, having attempted to go to Somalia or Syria, or of having provided support to a Belgian-based recruitment operation.
All 19 face the charge of "belonging to a terrorist group".
One of the accused, Brussels hairdresser Hassan Khafi, has admitted to the court that he left Belgium in 2011 in an attempt to join the Somali al-Shabaab militant group, which has links to al-Qaeda.
Khafi, 39, told the criminal court in Brussels that he had not taken part in fighting in Somalia and the al-Shabaab militants he met had not trusted the Belgians and had confiscated their passports, the Belga news agency reported.
He was arrested in Kenya in May 2012 and was extradited to Belgium last year.
Three of his associates are imprisoned there on charges of illegal entry but are expected to be sent back to Belgium shortly.
According to Le Soir daily, one of the three men in Kenya, Rachid Benomari, has appeared in photos brandishing a knife with which he promised to "cut the throat of infidels".
The Brussels trial, which is taking place under heightened security, comes amid mounting concern over the number of Belgians believed to be travelling to Africa, Syria and the Afghan-Pakistani border to fight alongside jihadist groups.
Scores of Europeans have already lost their lives in Syria's bloody three-year-old conflict, with more and more believed to be going to fight there.
The fear is that, upon their return to Europe, the now trained and experienced militants could help terrorist groups and boost recruitment.