Puigdemont was accompanied by four other former Catalan officials who are also wanted by Spanish authorities after they fled to Belgium last week after their removed from power by Spanish authorities as part of an extraordinary crackdown to impede the region's illegal declaration of independence.
According to AP, a spokesman for the Brussels prosecutor's office, Gilles Dejemeppe, said the five presented themselves to federal police and have been in custody since 9 a.m. (0800 GMT; 3 a.m. EST). He said that they have not been arrested and that Puigdemont and the four ex-ministers will be heard by an investigative judge Sunday afternoon.
The judge will have to decide what the next steps are within 24 hours. They could vary from arrest and imprisonment to conditional release. On Saturday, Belgian federal prosecutors said that they were studying the warrants and that they had shared them with city counterparts in Brussels.
The ousted officials and Puigdemont are wanted in Spain on charges of rebellion, sedition and misappropriation of public funds as part of their two-year bid to see Catalonia secede from Spain. On Friday, Spain issued a formal request to Belgium for extradition.