The news comes approximately two months after a deadly shooting at a Jewish Museum in Brussels that has been blamed on a Franco-Algerian man with links to another terrorist group, ISIL.
The 25-year-old man arrested on Tuesday evening had arrived from Greece at an airport in southern Belgium that is used predominantly by low-cost airlines, the Belga news agency reported.
The man was found in possession of fake French passports and two USB sticks containing videos of assassinations linked to al-Nusra militant group, which is active in Syria, Belga said.
The man, however, reportedly contended that he was a journalist who had infiltrated an al-Nusra camp and was later taken hostage by the group, but then managed to escape via Turkey and Greece.
He has nevertheless been charged with participation in the activities of a terrorist group, Belga wrote.
A senior militant leader in Syria said earlier that Britons make up the majority of foreigners in the most violent insurgent group.
Brig-Gen Abdulellah al-Basheer of the Free Syrian Army has urged the UK to help fight the ISIL terrorist group.
Basheer has written to British media, saying the ISIL keeps attacking other foreign-backed militant groups fighting the Syrian government. He has warned that ISIL members have been engaged in beheadings, crucifixions and the ill-treatment of women.
According to Basheer, ignoring the trend could lead to British extremists returning home to continue on their path.
NJF/NJF