The deal is the culmination of an agreement between the clubs which was initiated four years ago by Celtic chief executive Peter Lawwell and former manager Martin O'Neill.

Barcelona have the right to buy back Crosas in two years for Argentina forward Javier Saviola and Portugal winger Ricardo Quaresma earlier refused a similar deal.

"We would have taken Quaresma and Saviola but the players decided not to come," he told the Sunday Herald.

"We have always thought that this formula could be successful. So we have looked at Crosas.

"We are not finally there but that deal is now a structure which will hopefully allow us to add players going forward.

"Hopefully it makes a lot of sense. Not only with Barcelona but with other clubs too.

"A young or fringe Barcelona player could come here, play in our first team, play in front of 60,000 and in Europe and develop as a player. Both clubs could benefit from that."