Crosas was paraded in front of Celtic fans on Sunday

Celtic have completed the signing of Barcelona midfielder Marc Crosas on a reported four-year deal.

The 20-year-old was paraded at Celtic Park on Sunday prior to the Scottish champions' 1-0 SPL win over St Mirren.

Celtic will pay an initial £415,000 for Crosas rising to a potential £1.6m depending on appearances.

Celtic chief executive Peter Lawell told BBC Sport: "We're delighted. It's an innovative deal that benefits Celtic, Barcelona and the player."

The Scottish Premier League outfit have seen off competition from Sevilla, Sporting Gijon and Sampdoria for the defensive midfielder's signature.

The deal is the culmination of talks between the clubs that were first initiated four years ago by Lawwell and then manager Martin O'Neill.

The complex transfer gives Barcelona the right to buy back Crosas in two years for £1.65m, with the Glasgow club retaining 25% of his worth.

If the Catalan club do not take up that option, they would receive 25% of any transfer fee Celtic receive from another club.

"We've tried for years, since I started here, to consummate this great relationship with Barcelona," Lawell explained.

The Celtic chief revealed that Argentina forward Javier Saviola and Portugal winger Ricardo Quaresma earlier refused an opportunity similar to the one Crosas has accepted.

"We would have taken Quaresma and Saviola, but the players decided not to come. So, we're thrilled to resurrect it with Marc," Lawell said.

"I think we've got the structure in place where we can hopefully replicate the deal for different players."

Barcelona said on their website on Tuesday that they had agreed a deal "in principle" to sell Crosas to Celtic.

"Barcelona has the right to 25% of any possible future transfer," the club said on their official website.

Barcelona said Crosas's transfer to the SPL club included add-ons and revealed: "Also, Barcelona has an option of re-purchase at the end of the season 2009/10 for two million euros (£1.58m)."

Crosas, a defensive midfielder who played for Barca in pre-season friendly victories over Dundee United and Hibernian, made his first-team debut for Barcelona two seasons ago but has only made one appearance since.