BARCELONA (AFP) - Spanish football league champions Barcelona agreed a "long-term" contract extension with American sportswear giants Nike on Saturday, which will reportedly see the Catalan club surpass Manchester United with the most lucrative kit-sponsorship deal in the world.

Barca said the details of the deal will be revealed and ratified at the club's next general assembly.

Catalan sports dailies Sport and Mundo Deportivo reported, however, that the world champions could make up to a staggering €155 million (S$240 million) a season.

That would dwarf the current £75 million (S$150 million) a season, 10-year deal United agreed with adidas last year.

"FC Barcelona and Nike Inc have extended their current sponsorship deal, which was due to end on June 30, 2018," Barcelona said in a statement.

"The long-term agreement is a landmark in global football and builds upon a highly successful partnership.

"The details of the agreement will be reported and will have to be ratified at the next Club General Assembly."

A record-breaking deal with ease the strains on Barca's finances with a €420 million renovation of their Nou Camp stadium due to begin in 2018.

Moreover, the club are reportedly set to announce an extension to Brazilian star Neymar's contract - who is a key Nike-sponsored athlete - in the coming weeks.

"Through this new agreement with Nike we are extending a strategic alliance for the club, while also reinforcing our global position, hand in hand with the leading global sports brand," said Barcelona president Josep Bartomeu.

"We are excited by this new agreement and are confident that we'll be able to celebrate continued sporting successes together."

Despite sealing a 24th La Liga title last weekend, Barca are yet to agree a shirt sponsorship deal for next season, as talks with current sponsors Qatar Airways have stalled.