The only way Lionel Messi will legally be allowed to leave Barcelona on a free transfer is if he commits to not playing at all next season, according to a report.

Five-time Ballon d'Or winner Messi informed the Catalan giants last week that he wants to leave the club this summer after 19 years in Catalonia.

The Argentina international has missed Barca's first two training sessions back, allegedly because he believes that he is now technically a free agent.

However, the La Liga giants are disputing a clause in the forward's contract, claiming that it expired in June and he is now under contract for a further year.

ESPN suggests that Barca's interpretation is that he can only quit the club if he forgoes his salary for a season and does not join another club until next summer.

La Liga chiefs have sided with Barcelona, stating that Messi's contract is still active and that they will not facilitate a free transfer to another team.

Manchester City, managed by ex-Barca boss Pep Guardiola, are the strong favourites to sign the 33-year-old.