Barcelona, Jan 31 (IANS): Lionel Messi's contract with Barcelona is worth up to 555 million euros ($673 million) over four seasons, thus making his deal as the biggest signed by any athlete in sports history, says a report.

According to Spanish newspaper El Mundo, Messi would receive a maximum of 55,52,37,619 euros ($67,39,19,105) over four seasons, if a series of conditions were met.

The Spanish daily said it had access to the document Messi signed with Barcelona in 2017, which included fixed incomes and variables that could reach nearly 138 million euros ($167 million) each season.

Messi's 30-page contract, accessed by the newspaper, included a signing-on bonus of 11,52,25,000 euros for accepting the renewal and a "loyalty" bonus of 7,79,29,955 euros.

According to the newspaper, Messi has already earned 51,15,40,545 euros with five months still left to run on the deal which comes to an end this June.

The 33-year-old has been with the Catalan club for nearly two decades but had asked to leave at the end of last season after growing disappointments with events on and off the pitch at Camp Nou.

It was followed by the resignation of Josep Maria Bartomeu -- Barcelona president who agreed Messi's 2017 contract -- in October.

The Argentine has led Barcelona to LaLiga titles in 2018 and 2019, but the Champions League has eluded them.