Captain Lionel Messi has told Barcelona he wishes to leave the club immediately, a source confirmed on Tuesday.

The club source said Messi, who has spent his entire career at Barca, informed the club about his desire to leave by sending a burofax, a service used in Spain to urgently dispatch a document that requires proof to third parties.

The 33-year-old Argentine, who joined the club in 2000 as a youth player, has a contract with the Catalans until 2021.

Messi's decision to leave comes after the club's humiliating 8-2 defeat at the hands of Bayern Munich in the Champions League quarter-finals.

Messi has won a record six Ballon d'Or awards during his time at Barcelona and has helped the club win 10 La Liga titles and four Champions League crowns -- the club's last treble coming in 2015.