Spanish Prime Minister Mariano Rajoy gestures while giving a speech during a parliamentary session in Madrid, Spain, July 15, 2015. REUTERS/Paul Hanna

MADRID (Reuters) - Catalonia will not split from Spain, Prime Minister Mariano Rajoy said on Thursday, ahead of September elections in the north-eastern region being billed by Catalan leaders as a proxy vote on secession.

"There will be no Catalan independence," Rajoy told a joint news conference with the Polish premier, Ewa Kopacz.

Spain's central government has fiercely opposed attempts by Catalan leaders to hold a referendum on independence in the past.

Though the separatist movement has shown signs of waning in recent months, according to opinion polls, some pro-secession parties in Catalonia are teaming up ahead of the elections, which could give the drive fresh impetus.

(Reporting by Paul Day, Writing by Sarah White, Editing by John Stonestreet)