Lucas Paqueta is being investigated by the Football Association for imaginable betting regularisation breaches, sources person confirmed to the BBC.
The West Ham midfielder, 25, has been linked with a determination to Manchester City.
On Friday, Paqueta was omitted from Brazil's squad for their upcoming World Cup qualifiers "for him to benignant retired his problems".
Sky Sports reported Paqueta arsenic saying helium had not placed immoderate bets himself and was shocked by the reports.
The investigation, which is besides said to impact satellite governing assemblage Fifa, is believed to centre astir bets placed successful Brazil connected yellowish cards awarded against Paqueta.
Speaking connected Friday, Brazil's interim manager Fernando Diniz said Paqueta had been near retired of his squad for qualifiers against Bolivia and Peru adjacent month.
"Paqueta was connected the list, he's a subordinate I similar a lot. It's a clip for him to resoluteness these issues," Diniz told reporters.
"People request clip to benignant these issues out. He's a subordinate I love, I person the champion impressions of him."
BBC Sport has approached the FA and West Ham for comment.
Paqueta joined the Hammers from Lyon for £36.5m past summertime and was instrumental successful the nine winning the Europa Conference League.
He made 28 Premier League appearances past season, scoring 4 goals and assisting three.
City brag Pep Guardiola said successful a quality league connected Friday that Paqueta "is a West Ham player" and would not remark connected a imaginable transfer.
In May, Brentford guardant Ivan Toney was suspended from shot for 8 months for 232 breaches of the FA's betting rules.
- Latest West Ham United news, investigation and instrumentality views
- Get Hammers quality notifications
- Listen to the latest The Far Post podcast
- Our sum of West Ham United is bigger and amended than ever earlier - here's everything you request to know to marque definite you ne'er miss a moment
- Everything Hammers - spell consecutive to each the champion content