MADRID (Reuters) - The Basque Country will seek more autonomy from Spain, its regional government chief said as he was sworn in for a second four-year term on Thursday, potentially putting him on course for a showdown with Madrid.

Inigo Urkullu, whose center-right Partido Nationalista Vasco (PNV) won a regional election in September but fell short of an absolute majority. He was voted in thanks to the backing of the Socialists in an example of the right-left deals that define Spain's new political landscape.

Last month conservative Prime Minister Mariano Rajoy won the confidence of the national Spanish parliament for a second term in office after the Socialists abstained in an investiture vote that ended a 10-month political stalemate.

While the Basque nationalist movement has not been as much of a problem for the central government as Catalonia's secessionist push, it could potentially gather strength over the coming months.

"The Basque Country is a nation that has to be recognized as such," Urkullu said in a speech to the regional parliament. "We have an opportunity to reach a new pact for the future," he added.

The Basque Country is already one of the most autonomous regions in Europe, with powers to raise its own taxes and control over where most of that revenue goes.

Like Catalonia, it has its own police and controls policy areas ranging from education to health and jobs.

But both regions would like to go further and be recognized as nations in the Spanish constitution, which would give them the right to decide whether they want to remain part of Spain or break away.

Most of Spain's main parties, including the ruling center-right People's Party and center-left Socialists oppose this.

(Reporting by Amanda Calvo; Editing by Julien Toyer and Pravin Char)