BRUSSELS: German Chancellor Angela Merkel and French President Emmanuel Macron voiced strong support for Madrid in the Catalan independence crisis on Thursday, backing the Spanish government´s response to the country´s worst political crisis in decades.

EU leaders gathering for a summit in Brussels closed ranks behind Spanish Prime Minister Mariano Rajoy, saying the standoff over Catalonia's independence drive must be settled within the provisions of Spain´s constitution.

The show of unity comes as Madrid vowed to take back some of the Catalan regional government´s powers and its leader warned he could declare independence, deepening the crisis still further.

"We back the position of the Spanish government," Merkel said as she arrived for the summit. "We hope there are solutions found on the basis of the Spanish constitution."

Brussels has insisted the dispute over Catalonia´s independence referendum is an internal matter for key EU member Spain, backing Madrid´s position that the vote was illegal, but calling for dialogue.

France has been outspoken in its support of the Madrid government during the crisis, with Macron charging recently that the separatists were motivated in part by "economic selfishness".

The French president told reporters in Brussels he expected the 28 EU leaders to voice solid support for Madrid.

"This European Council will be marked by a message of unity -- unity with our member states facing crises, unity with Spain and very strong unity in discussions about Brexit," he said.

But a senior EU source said the crisis was not on the agenda for the summit and he did not expect leaders to make a statement on the subject.

Rajoy waved to waiting journalists but remained silent as he arrived at the summit building, where he was greeted with a bear hug by European Commission President Jean-Claude Juncker.

Luxembourg´s Prime Minister Xavier Bettel reiterated the oft-rehearsed European line that the crisis in Catalonia was an internal matter for Madrid.

"The Catalan problem is above all a Spanish problem, it must be resolved in Spain," he said.

Belgian Prime Minister Charles Michel, whose ruling coalition at home includes Flemish separatists, urged moderation and dialogue.

"I appeal for a de-escalation, I don´t think we will find a solution that is in everyone´s interest through political escalation," Michel said.

Michel caused consternation in Madrid the day after the Catalan referendum in which Spanish police cracked down hard to try to prevent voting, sending a tweet condemning the use of violence.

Catalan leader Carles Puigdemont says his regional administration has a mandate to declare independence from what he says was a 90-percent "Yes" vote in a referendum on October 1, marred by a heavy-handed police crackdown on voters.

Spain -- and its EU partners -- have refused to recognise the vote, saying it was conducted in defiance of court rulings deeming it illegal and unconstitutional.