BRUSSELS (AP) — Belgian authorities say they are keeping a 22-year-old man in custody on suspicion that he was planning to carry out a "terrorist offence."

The Federal Prosecutor's Office said Thursday that the Belgian man, identified only as Hajar A., was remanded in custody for a month by a court in the city of Liege.

The court issued an arrest warrant for the man on Aug. 25. He is charged with "having left national territory with a view to committing, in Belgium or abroad, a terrorist offence."

Belgium has been on high alert since suicide bombers killed 32 people at the Brussels airport and a subway station last year.