Mr. Bekaert emphasized his âmore than 30 years of experience with extradition and political asylumâ cases, including with Basques who were fighting extradition to Spain to face trial on terrorism charges.
Belgium is virtually the only national government in Europe that has been even remotely sympathetic to Mr. Puigdemontâs pleas for mediation, not least perhaps because the country has faced separatist tensions of its own led by Flemish hard-liners.
Awkwardly, Brussels is also the headquarters of a European Union bureaucracy that has held the Catalan secessionists at armsâ length, for fear of upsetting Spain, one of the blocâs largest member states, and stoking forces of fragmentation in other parts of the Continent.
On Monday, while there was no official confirmation that Mr. Puigdemont had gone to Brussels, the Belgian and Spanish news media variously suggested that he had arrived for consultations, to seek political asylum, or to even declare a Catalan âgovernment in exile.â
The speculation kicked into high gear not long after Spainâs attorney general, JosÃ© Manuel Maza, called around noon in Madrid for the prosecution of Mr. Puigdemont and 19 other Catalan politicians, stopping short of ordering their immediate arrest.
Mr. Maza said he wanted the Catalan politicians to appear âurgentlyâ in court in Madrid. A decision would be left to Spanish judges whether to charge or jail them. The politicians could face 30 years in prison for the most serious of the potential charges, which included rebellion and sedition.
Officially, the Belgian government said it had no knowledge of Mr. Puigdemontâs presence in the country.
But the statements of some officials seemed to hint at an openness to accepting Mr. Puigdemont and other Catalan officials if they chose exile.
âIt is not unrealistic, if you see the situation at this moment, and the repression from Madrid and the prison sentences with which they are threatening, that the question is whether such a person still has a chance to a fair trial of course,â Belgiumâs migration minister, Theo Francken, told VTM News, a Belgian television station, over the weekend.
âThatâs where we enter into a difficult diplomatic situation with the Spanish government,â he added.
Mr. Francken is a member of the New Flemish Alliance party, which favors Flemish independence from the rest of Belgium and has historically had strong links to the Catalan separatists as a kindred movement. This month, members of the alliance hung the Catalan independence flag â the Estelada â in the Belgian Parliament, in a gesture of support.
But Belgiumâs prime minister, Charles Michel, has dismissed the possibility of granting asylum to Mr. Puigdemont, saying it âis absolutely not on the agendaâ and called on Mr. Francken ânot to fan the flames.â
Mr. Puigdemontâs arrival presents a direct challenge to Mr. Michel, a Federalist, who as the leader of a delicate government coalition will have to keep separatists in his own government in check while trying to maintain good diplomatic relations with Spain.
The Spanish news media had reported that Mr. Puigdemont had left Catalonia with five other deposed members of his cabinet, traveled by car to the southern French city of Marseille, and then by plane to Brussels.
In Spain, officials from Prime Minister Mariano Rajoyâs conservative Popular Party said their priority on Monday was to make sure Mr. Puigdemont did not try to stay in office, by insisting he remained leader of Catalonia, rather than worry about him escaping the country.
Fernando MartÃnez-MaÃllo, a senior Popular Party official, characterized Mr. Puigdemontâs departure as âa desperate act.â
Albert Rivera, the leader of the Ciudadanos party, which is strongly opposed to secession, accused Mr. Puigdemont and his separatist leadership of âfleeing the countryâ while leaving his Catalan civil servants to resist and continue to break Spanish law.
Indeed, the forcible steps by the central government have now left Catalan civil servants and politicians with the painful choice of sticking to their secessionist plans and defying Madridâs direct administration or facing the potential of criminal charges.
Not least, there was the important decision for separatist parties about whether to take part in regional elections called by Madrid or to risk sidelining themselves.
The two main Catalan parties â including Mr. Puigdemontâs Catalan European Democratic Party â said on Monday they would run in the elections, which are scheduled for Dec. 21, although perhaps no longer as part of the coalition that won the most parliamentary seats in 2015.
GermÃ Bel, a separatist Catalan lawmaker, said Mr. Puigdemontâs possible hopes of running a government from exile was âsymbolic.â
âI donât know of anyone whoâs run a government from overseas,â he said. âEven Charles de Gaulle didnât run a government from overseas.â
But he argued that it would be hard for Mr. Rajoyâs government to maintain control over Catalonia for an extended period.
The decision by pro-independence parties to take part in the December elections meant that they âat least implicitlyâ accept they are still part of Spain â no small concession.
âThis election has been called by the Spanish government under Spanish law â and it will be an election run within the state,â Mr. Bel said.
With the emergency measures taken over the weekend, Mr. Rajoy opted not to appoint a caretaker leader of Catalonia.
Instead, the countryâs deputy prime minister, Soraya SÃ¡enz de SantamarÃa, took over the management of the Catalan administration from Madrid, and dispatched a senior central government official to Barcelona on Monday.
Juan Ignacio Zoido, the Spanish interior minister, said on Monday that the takeover of the Catalan police force, known as the Mossos, had gone smoothly. He fired the Mossos police chief, Josep LluÃs Trapero, over the weekend and appointed the deputy leader of the force, Ferran LÃ³pez, to the post.
Under the emergency measures allowed by Article 155 of the Spanish Constitution, the provision invoked by Mr. Rajoy to take control of Catalonia, the national government could replace the 17,000 officers of the Mossos with Spanish police officers.
But Mr. Zoido said that âat no point did we consider eliminating the Mossos police corps.â
Mr. Zoido called on separatist leaders to remove their personal belongings from their offices on Monday and to leave, focusing solely on preparing for the December elections, as candidates.
At least one member of Mr. Puigdemontâs ousted cabinet, Josep Rull, defiantly went to work Monday morning, after the regionâs president sent a message over the weekend urging Catalans to peacefully oppose Madridâs takeover and the removal of a democratically elected regional government.
After spending one hour in his office, Mr. Rull, the Catalan minister for planning and sustainability, left in a waiting car, but without his police detail, telling reporters that he had not removed his belongings from his office.
âToday I came to my office to carry out the work that the Catalan people entrusted to us,â he said. âAnd now I will continue, normally, with my agenda.â
The possibility that separatist leaders might be charged with rebellion has prompted a major dispute among Spanish lawyers.
Diego LÃ³pez Garrido, who drafted changes to the Spanish legal code relating to rebellion, told Antena 3 that âin my judgment, there is no crime of rebellion because no violence has been produced.â