Catalonia's deposed leader Carles Puigdemont and four former advisers have turned themselves in to Belgian police, says a prosecutors' spokesman.
He said an investigating judge would decide by Monday morning whether to execute an EU arrest warrant issued by a Spanish judge on Friday.
Mr Puigdemont fled to Belgium after Madrid imposed direct rule on Catalonia following an independence referendum.
He has said he will not return to Spain unless he is guaranteed a fair trial.
He and his four associates are wanted on charges of rebellion, sedition, misuse of public funds, disobedience and breach of trust following the referendum which a Spanish court deemed unconstitutional.
Last week, Spanish Prime Minister Mariano Rajoy imposed direct rule on Catalonia, dissolved the regional parliament and called local elections for 21 December.
Mr Puigdemont's associates also now in custody are Meritxell Serret (former agriculture minister), Antoni Com�n (former health minister), Llu�s Puig (former culture minister), and Clara Ponsat� (former education minister).
They all handed themselves in to Belgian federal police, accompanied by their lawyers, at 09:17 local time (08:17 GMT) on Sunday, said Gilles Dejemppe, a spokesman for Belgian prosecutors.
They will be heard by the investigating judge who will then "have 24 hours, until 09:17 on Monday, to decide whether to refuse the European Arrest [Warrant], arrest them, release them under conditions or grant bail", Mr Dejemppe said.
If the judge decides to go ahead and arrest them, Belgium has a maximum of 60 days to return the suspects to Spain. But if the suspects do not raise legal objections, a transfer could happen much sooner.

(Source: BBC)