Ex-Catalonia leader Carles Puigdemont in custody in Belgium
Catalan ex-president Carles Puigdemont and four other former regional ministers have turned themselves in to police in Brussels, federal prosecutors in Belgium said.
A spokesman for the Brussels' prosecutor's office, Gilles Dejemeppe, said the five presented themselves to federal police and have been in custody since 9am local time.
He said that they have not been arrested and that Mr Puigdemont and the four ex-ministers would be heard by an investigative judge on 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.
A European arrest warrant has been issued for Mr Puigdemont and the other four as Spain seeks their return for an investigation related to Catalonia's independence bid.
They had fled to Belgium this week after being removed from power by Spanish authorities as part of an extraordinary crackdown to impede the region's illegal declaration of independence.
The separatist politicians are wanted in Spain on suspicion of rebellion for pushing through a declaration of independence for Catalonia in violation of Spain's constitution.
Mr Dejemeppe said the judge's options range from "refusal to execute the European arrest, arresting the people involved, releasing them on conditions or under bail".
He said if they were arrested then they would be sent to jail as the extradition process continued.
Mr Dejemeppe said that the entire process from arrest to extradition could take more than 60 days.
That delay could give Mr Puigdemont time to participate, albeit from afar and in largely a symbolic capacity, in the snap regional election called by Spain's government for Catalonia on December 21.
A senior official of Mr Puigdemont's party, the centre-right Democratic Party of Catalonia, said on Sunday that the party wanted Mr Puigdemont to continue as its candidate.
Spanish government spokesman Inigo Mendez de Vigo has said that any politician can stand in the election unless he or she has been convicted of a crime.
Mr Puigdemont and the four ex-ministers fled to Belgium in the past week after being removed from power by Spanish authorities as part of an extraordinary crackdown to quash the region's illegal secession claim.
A Spanish National Court judge issued warrants for them on suspicion of five crimes, including rebellion, sedition and embezzlement, on Friday, a day after the same judge sent another eight former Catalan cabinet members to jail without bail while her investigation continues.
A ninth spent a night in jail and was freed after posting bail.
Mr Puigdemont wrote in Dutch on his Twitter account on Saturday that he was "prepared to fully co-operate with Belgian justice following the European arrest warrant issued by Spain".
Mr Puigdemont's lawyer in Brussels had previously said that his client planned to fight extradition to Spain without requesting political asylum.
Political forces in Catalonia are hurriedly jockeying for position to start a campaign that promises to be as bitter as it is decisive to Spain's worst institutional crisis in nearly four decades.
While pro-union parties try to rally support to win back control of the regional parliament in Barcelona, pro-secession parties are debating whether or not to form one grand coalition for the ballot.
Parties have until Tuesday to register as coalitions or they must run separately.
Catalan ex-regional president Artur Mas, the first leader to harness the political momentum for secession, told Catalan public television on Sunday that he backed a fusion of parties for the December vote.
But, he said, the main goals must be to recover the self-rule of the region and the release of the jailed separatists.
"Under these exceptional circumstances that our country is going through, don't we have to substitute the normal and logical competition for the co-operation we all need?" Mr Mas said.
"If we add the issue of independence, we won't get as many people to support us."
The separatist majority of Catalonia's parliament defied Spanish authorities and voted in favour of a declaration of independence on October 27.
The next day, Spain's central government used extraordinary constitutional powers to fire Catalonia's government, take charge of its administrations, dissolve its regional parliament and call a regional election.
Spain's constitution says the nation is "indivisible" and that all matters of national sovereignty pertain to the country's parliament.
In all, Spanish prosecutors are investigating 20 regional politicians for rebellion and other crimes that could be punishable by up to 30 years in prison.
Another two leaders of pro-secession grassroots groups are also in jail while an investigation continues into suspicion of sedition.
Hundreds of pro-secession Catalans gathered in town squares across the region on Sunday to put up posters in support of independence and to demand the release of the jailed separatists.
"People came today because we want to send a message to Europe that even if our president is still in Brussels and all our government now is in Madrid, jailed, that the independence movement still didn't finish and people are still striving to get independence in a peaceful and democratic way," said 24-year-old protester Adria Ballester in Barcelona.
The grassroots group Catalan National Assembly has also called for a strike on Wednesday and a public protest on Saturday.