DOHA. Lionel Messi has signed an agreement worth more than $20 million to promote digital fan token company Socios.com, a source close to the deal told Reuters on Tuesday.

Messi becomes the latest global sports personality to enter the crypto world following NFL quarterback Tom Brady and NBA star LeBron James and the deal is part of a growing wave of tie-ups between crypto firms and soccer.

Paris St Germain and Argentina forward Messi, whose move from Barcelona in August included a cryptocurrency payment, will be involved in a publicity and promotion campaign for Socios in the build-up to the Qatar World Cup, which starts in November.

The 'ambassador' deal for Messi does not include crypto payments and is a three-year agreement, the source said.

Socios have signed deals, including creating tokens, for over 130 sports organisations including a number of top soccer clubs such as PSG, Barcelona, Juventus and Manchester City.

Fan tokens are a type of cryptocurrency that allow holders to vote on mostly minor decisions related to their clubs.

The tokens are increasingly seen by clubs as a source of new revenue but have been criticised by some supporters groups who see their introduction as superficial participation that adds to the already growing costs of following their teams.

Brady last year took an undisclosed equity stake in crypto exchange platform FTX Trading Ltd and became an ambassador for the company.

In January, James announced a multi-year partnership with Crypto.com, a company who recently signed a sponsorship deal with world soccer's governing body FIFA.