Carles Puigdemont, Catalonia's deposed president, has been freed from police custody in Brussels, along with four of his former ministers, on bail and pending trial.
The former Catalan leader, who is conditionally released, is expected to appear in a Belgian court soon over his possible extradition.
The arrest warrant, which Puigdemont is expected to contest, was issued on Friday and includes charges such as disobedience, sedition and misuse of public funds.
Al Jazeera's Nadim Baba, reporting from Brussels, said that the charges in the warrant carry a possible jail sentence of 30 years.
"This is extremely serious. Lots of people were wondering if the five Catalan politicians started the process to apply for political asylum, something Puigdemont said he was not interested in. At the moment that is not an issue," he said.
"The five are expected to appeal if Belgian legal authorities decide to extradite them back to Spain in the coming months. Beyond that, political asylum can buy them more time, but it would be really unusual for Belgium to issue political asylum to another EU member state."
The extradition of the Catalan politicians is a fully judicial issue in the hands of judges.
Violence 'not an option'
Puigdemont told Belgian media on Sunday that he did not flee Spain but travelled to Brussels to avoid violence. "Violence has never been an option for us," he had said.
Catalonia has been in political upheaval since October 1, when the region held a disputed referendum on independence from Spain.
Sunday's developments came as a poll showed Catalan separatist parties might fall short of an absolute majority in the December 21 regional elections, calling into question the political future of the secessionist bid.
Spain called the vote following the dissolution of the Catalan government for its independence declaration.
Pro-secession parties would win roughly 46 percent of the vote, according to Madrid-based pollster GAD3.
This would mean a loss of 1.8 percent since the last regional elections in 2015.
The poll was published on Sunday in La Vanguardia, a Catalan daily.
Secessionist parties would win between 66 and 69 seats in the Catalan parliament. An absolute majority would require 68 seats in the 135-seat body.
Source: Al Jazeera News