Miami (AFP) - Inter Miami on Wednesday announced the signing of Brazil star Casemiro but Major League Soccer immediately said it was investigating allegations of tampering by the club over the deal.

Casemiro, who has 91 caps for Brazil and won five Champions League titles with Real Madrid, was a free agent after Manchester United opted not to renew his contract following a mixed four-year stint at the Premier League giants.

The veteran 34-year-old midfielder opted to join Lionel Messi and Rodrigo De Paul at Inter Miami, which is co-owned by David Beckham.

“Casemiro’s arrival reflects the vision and ambition that define Inter Miami. We never settle. We’re always looking to grow, improve, and raise our standards every season,” said Inter Miami managing owner Jorge Mas.

“We’ve built a global club with the vision of becoming not only the best club in the United States, but also a benchmark globally.”

But just moments after the announcement, MLS said in its own statement that the North American soccer league was “reviewing a tampering allegation against Inter Miami CF.”

The probe concerns the MLS’s system of “discovery rights,” which must be acquired by a club before they can start negotiating to sign specific high-profile players.

Los Angeles Galaxy had held the discovery rights to negotiate with Casemiro, and is understood to be receiving compensation from Inter Miami.

“The league is gathering all relevant information and will refrain from further comment until the review is complete,” said the MLS.

“While Inter Miami CF and the LA Galaxy have reached a settlement for the Discovery Priority to sign Casemiro, the terms will be released upon conclusion of the tampering investigation.”

While other clubs have international marquee talent, like Los Angeles FC’s Son Heung-min, signing Casemiro consolidates Inter Miami as the most star-packed club in MLS.

Inter Miami won its first ever MLS Cup title in December, and moved into a brand-new stadium in April.

But the club has run into trouble over transfer dealings before.

In 2020, French World Cup winner Blaise Matuidi’s move to Inter Miami from Juventus triggered an MLS investigation that resulted in the club being hit with a $2 million fine for breaching salary cap regulations.

The MLS last week returned from a World Cup mid-season break, and is hoping to tap into enthusiasm for soccer sparked by the giant tournament.

“Thanks, world, we’ll take it from here,” reads a recent MLS campaign slogan.

In a statement release by the club, Casemiro said he was motivated to sign for Inter Miami by “winning and continuing to grow.”

“The project the Club presented to me, along with the effort everyone made to bring me here, means a lot to me,” he said.

Co-owner Beckham added: “He is a winner who has achieved so much in the game and after such an incredible career with Real Madrid and Manchester United I’m delighted that he’s decided to make Miami his next home.”