Barcelona talisman Lionel Messi has reportedly been considering leaving the club since March.

The six-time Ballon d'Or winner submitted a transfer request earlier this week, asking to bring an end to his 19-year association with Barcelona, who are the only club he has ever played for professionally.

The news came less than two weeks after Barca had slumped to an 8-2 Champions League defeat at the hands of Bayern Munich - a result which capped off a trophyless and turbulent campaign for the club.

However, Spanish journalist Guillem Balague claims that Messi first informed the club that he was thinking of leaving when he stopped talks over a new contract back in March.

Balague claims that Barca president Josep Maria Bartomeu was told in April, June, July and August that they should prepare for Messi's exit, but that he did not consider it a realistic possibility.

Barcelona remain desperate to keep their talismanic skipper at the club and Bartomeu has offered to resign if it means Messi will stay - although they are also confident that the Argentine will not be able to leave on a free transfer.

Messi has scored 634 goals in 731 games for the club and is widely regarded as one of the greatest players in football history.

Manchester City, Manchester United, Paris Saint-Germain, Chelsea, Juventus and Inter Milan are among the clubs to have been linked with a move for the Argentina international.