Puigdemont was sworn in late Sunday, after months of quarrelling between the separatist parties holding the majority in the regional parliament. The lawmakers only had until Monday to chose a new Catalan leader, in order to avoid going back to the polls.

"We begin an extremely important process, unparalleled in our recent history, to create the Catalonia that we want, to collectively build a new country," Puigdemont told the parliament.

He added that Catalonia would need to negotiate with the Spanish state, the European Union and the international community to achieve this goal.

The pro-independence lawmakers agreed on an 18-months "roadmap" to full independence in November. The conflict, however, arose around the previous separatist leader Artur Mas, when the far-left CUP party refused to back him over his support for austerity and corruption scandals linked to his party.

In an last minute move, Mas agreed to step aside on Saturday and proposed the lesser-known Puigdemont as his successor.

The Spanish newspaper El Pais quoted Puigdemont, a 53-year old journalist and mayor of the Catalan city of Girona, as saying he wants to "chase the invaders out of Catalonia."

United front in Madrid

Commenting on Puigdemont's appointment on Sunday, the acting Spanish Prime Minister Mariano Rajoy warned he would block any unilateral move from the new Catalan government.

"I will defend and preserve democracy all over Spain. I will defend the sovereignty of the Spanish people," he told a news conference.

Rajoy is struggling to form a coalition government after his conservative Popular Party (PP) came top in the December 20 elections but lost its absolute majority.

However, the Catalan drive for independence might force the lawmakers in Madrid to compromise, as Rajoy's rivals from the Socialist party said they support his efforts to preserve national unity.

"We reiterate our support for the caretaker government to enforce the law and defend the Constitution," Socialist lower house parliamentary group spokesman Antonio Hernando told reporters.

Spanish central government already refused to allow a Catalan referendum in 2014, arguing that such a poll would violate the country's constitution. Spain's Constitutional Court also struck down a November resolution detailing the 18-month road to independence.

dj/bw (Reuters, AFP, dpa, AP)