The Junts per Catalunya political rally on Monday. Manu Fernandez / AP

In a surprise move that comes just as the campaign for regional elections in Catalonia is getting underway, Spain’s Supreme Court on Tuesday withdrew European arrest warrants for sacked Catalan premier Carles Puigdemont and four ministers of his ousted government who fled to Belgium after the Catalan parliament unilaterally declared independence in October.

However, Puigdemont and the four ministers – Antonio Comín, Lluís Puig, Meritxell Serret and Clara Ponsatí – still face Spanish arrest warrants and would be arrested on their return to Spain, according to court sources.

The decision comes amid concerns that the involvement of the Belgian judicial system could hamper attempts by the Spanish courts to try Puigdemont and the four ministers for rebellion, the most serious crime for which they are being investigated, and one which carries a maximum sentence of 30 years.

The latest Supreme Court decision comes a day after it decided to release six Catalan politicians from pre-trial custody

The Spanish crime of rebellion does not have an exact equivalent in Belgium, a fact which could have seen Belgian authorities handing over the sacked politicians to Spanish authorities on charges such as misuse of public funds, but not on charges of rebellion. This in turn would have prevented the Spanish courts from trying Puigdemont and the former ministers for the crime.

In his ruling on the matter of the European arrest warrants, Supreme Court justice Pablo Llarena said that maintaining them could “restrict” actions against the politicians – something that would also create a paradoxical situation in which the Catalan independence figures in Belgium would be in a better position than those who remained in Spain.

In the same vein, the judge also noted that rebellion is a collective crime and that those being investigated “may have acted in concert.” For this reason, the investigation has to be carried out in a “unified manner” to avoid legal confusion and differing treatment for the various suspects.

The latest Supreme Court decision comes a day after it decided to release six Catalan politicians from pre-trial custody but to keep the two most prominent ones behind bars.

The decision comes amid concerns the involvement of the Belgian judicial system could hamper attempts to try Puigdemont for rebellion

Former deputy premier Oriol Junqueras, of the Catalan Republican Left (ERC), and his ex-minister for interior affairs Joaquim Forn will remain in detention after Llarena determined that there is a risk that both would go back to committing the same crimes if released.

The heads of two prominent pro-independence associations are also being kept in custody while an investigation into rebellion, sedition and misuse of public funds is underway in connection with the illegal independence drive.

Puigdemont and the four former ministers currently in Belgium had been scheduled to appear before a Belgian judge on December 14 in a hearing to decide on whether European arrest warrants would be executed.