Spain warned Monday that Madrid would maintain its unpopular direct control over Catalonia if former regional leader Carles Puigdemont tries to govern again from exile in Belgium.

Speaking to party members in Madrid, Prime Minister Mariano Rajoy said Puigdemont had "to be physically present" in Catalonia to take office.

And if that didn't happen, he warned, the central government would maintain the direct rule imposed after Catalan leaders declared independence in October.

Puigdemont is the separatist camp's favoured candidate to lead Catalonia again after pro-independence parties won an absolute majority in regional elections on December 21.

But he is in self-imposed exile in Belgium and if he returns, he risks arrest on charges of rebellion, sedition and misuse of public funds for his role in the region's failed independence bid.

On Twitter, Puigdemont responded by pointing out to Rajoy that his conservative Popular Party had only "secured four lawmakers on December 21 and continues to govern Catalonia from Madrid."

By contrast, Puigdemont's Together for Catalonia list won 34 seats in the best result for a separatist grouping, with anti-independence party Ciudadanos taking 36.

Ciudadanos, however, does not have enough allies to get a majority while Together for Catalonia will likely join forces with the leftwing ERC, which got 32 seats, and the smaller CUP party, which took four, to get an absolute majority.

- Remote control? Unlikely -

To be elected regional president Puigdemont should, in theory, be present at the parliamentary session where the vote takes place, but he wants to appear by videolink or write a speech and have it read by someone else.

If that is allowed, he could then officially take office from Belgium and try to govern the region remotely.

But legal experts doubt this would be feasible, and even Puigdemont's allies -- the leftwing ERC of his former vice-president Oriol Junqueras -- are scratching their heads.

ERC spokesman Sergi Sabria said Monday the parties were looking into all possible ways to have Puigdemont sworn in that wouldn't be branded illegal by the courts in order to end Madrid's direct control as soon as possible.

Madrid's direct rule has proven very unpopular in a region that had enjoyed considerable autonomy before its leaders attempted to break away from Spain.

In response, Rajoy seized control, sacked Catalonia's government, dissolved its parliament and called snap elections in December.

On Wednesday, the Catalan parliament holds its first session, and it has until January 31 to hold a debate on choosing a regional president.