The unity of Belgian Prime Minister Charles Michel's government rests on a deal between Liberals and nationalists | Olivier Hoslet/EPA Catalonia crisis hits home in Belgium Ousted Catalan leader Carles Puigdemont turns up in Brussels, unsettling local politics.

Barcelona's feverish politics are giving Brussels a cold.

The reports of the ousted Catalan leader coming to Belgium and seeking refuge on Monday threatened to upset a delicate political balance between Flemish nationalists and other government parties.

As the crisis in Catalonia has played out, it has divided Belgian politics. Flemish nationalists who have at times called for the breakup of Belgium sided openly with the separatists in northeastern Spain, which makes their coalition partners in the federal government anxious.

Those divisions came out into the open over the weekend and into Monday. On Saturday night, a prominent member of the New Flemish Alliance (N-VA), a Belgian nationalist party that belongs to the four-party ruling coalition, said the ousted Catalan president Carles Puigdemont could seek asylum in Belgium. On Monday, Madrid filed criminal charges against Puigdemont.

The same day, Spanish media reported that the separatist leader had arrived in Brussels along with five Cabinet members to take up the minister's suggestion. A European Parliament source confirmed to POLITICO the Catalan leader was in Belgium.

The ensuing kerfuffle upset the uneasy peace between the four parties that Prime Minister Charles Michel, a French-speaking liberal, has managed for the past three years. It also gave a preview of the likely tenor of the next election campaign, due in 2019.

Sympathy for the Catalans

The N-VA pushed back against suggestions the proposition to the former Catalan leader from Theo Francken, the secretary of state for asylum and migration, represented its official policy. A spokesperson for the N-VA, Joachim Pohlmann, told POLITICO that “in case Mr. Puigdemont is in Brussels, he’s certainly not here at the invitation of the N-VA.”

Jan Jambon, the interior minister and deputy prime minister from the N-VA, was not aware Puigdemont was coming to Brussels, his spokesman Olivier Van Raemdonck said. “Everyone knows Jan Jambon and the N-VA are sympathetic towards the Catalans. But that’s something completely different than sitting down with the man as a member of the federal government,” he added.

Still, Francken's original suggestion to harbor the Catalan leader — echoed on Twitter by the minister later as well — is read as a frank endorsement of Catalonia's separatist agenda.

That's a problem for Michel, because the unity of his government rests on a deal between liberals and nationalists, under which the nationalists have put their separatist agenda on ice.

Now that Flemish nationalists are waving the separatist flag again, Michel faces a risk of seeing a Spanish-style crisis break out in Belgium.

On Sunday, he pushed back against Francken by asking him "not to add fuel to the fire." Belgian officials stressed that the junior minister was not speaking for the Belgian government.

"We really shouldn't be importing Spanish problems," said a government official, asking not to be named due to the issue's sensitivity.

Whither the Flemish nationalists

If Michel is under pressure, the nationalists are also in a tricky position.

Less than a year ago, Interior Minister Jambon implied that recognizing a Catalan independent state would be worth risking the survival of the current coalition government for. The N-VA’s vice president, MEP Sander Loones, then told De Morgen that “it’s a key principle for us that peoples have the democratic right to define their own fate, also within the EU.”

Now, having rebranded itself as a conservative Belgian force, the party is once again flirting with pro-independence demands in the run-up to the 2019 election.

Siding with the Catalan leader's request for asylum would pit the N-VA against its coalition partners, especially the French-speaking liberal MR party of Prime Minister Michel.

“The situation in Catalonia, this is difficult to just let something like that pass by" — Dave Sinardet

Michel's office did not respond to a request for comment.

Puigdemont on Monday sought legal advice from Belgian lawyer Paul Bekaert, a specialist in human rights law who has defended Basque militants' requests for citizenship in the past, news agency Belga wrote. Bekaert said he would defend Puigdemont.

If the Catalan leader is to get asylum under Belgian law, he would have to prove that he is in serious and imminent danger in Spain, that his prosecution is disproportionate and that it violates international human rights principles.

Francken's off-the-cuff suggestion "means a member of the government, is openly and publicly questioning the rule of law in Spain," said Dave Sinardet, a Belgian political analyst and academic who studies separatist movements globally. He said "in that sense, it is a far-reaching incident."

But the political temptation may be too great for the Flemish nationalists, Sinardet said: "The situation in Catalonia, this is difficult to just let something like that pass by."

Harry Cooper contributed to this article.