Carles Puigdemont and four of his political allies were released with conditions in Belgium on Sunday after turning themselves in to face a Spanish warrant for their arrest.
A judge ordered the five, who fled Spain earlier this week after being accused of rebellion and sedition, not to leave Belgium until their extradition case is heard.
It is the latest twist in the crisis unleashed by the Catalan separatists’ push to break away from Spain, sending shock waves across Europe.
Mr Puigdemont and his allies escaped to Belgium last Monday after Spain dismissed the Catalan executive and imposed direct rule on the semi-autonomous region following the declaration of independence by the parliament there last month.
“They were taken into custody at 9:17 am (0817 GMT),” said Gilles Dejemeppe, a spokesman for Belgian prosecutors.
A white van believed to be carrying Mr Puigdemont raced out of the Belgian prosecutor's office around 15 hours later, AFP reporters witnessed.
“The request made this afternoon by the Brussels’ prosecutor’s office for the provisional release of all persons sought has been granted by the investigative judge,” said the statement by the prosecutor’s office shortly afterwards.
The next court hearing will be in the following 15 days. Belgium has up to 60 days to decide whether to send the Catalans back to Spain.
Mr Puigdemont’s PDeCAT party said Sunday that he had turned himself in to show his “willingness not to flee from the judicial process but to defend himself in a fair and impartial process, which is possible in Belgium, and highly doubtful in Spain”.
Mr Puigdemont wrote on Twitter on Saturday that he and his colleagues - Meritxell Serret, Antoni Comin, Lluis Puig and Clara Ponsati - would cooperate with the Belgian authorities.
Spain issued European arrest warrants on Friday after Puigdemont and his allies ignored a summons to appear before a judge on allegations linked to the move to declare Catalonia an independent republic.
The judge in Madrid had on Thursday put Mr Puigdemont’s deputy and seven other deposed regional ministers behind bars because of a risk they would flee.
