Eintracht Frankfurt have reported West Ham to FIFA after claiming they are owed an overdue payment of £5.4m from the sale of Sebastien Haller last summer.
The French striker became the Hammers' record signing when he joined for £45m from the German side, with the Irons fending off interest from across Europe to secure the 26-year-old's signature.
It is thought West Ham paid 75% of the fee up front with the remaining quarter paid in instalments, the latest of which was due on 15 May but as of yet has not been paid. Eintracht have responded to the delay and West Ham may face the threat of sanctions by FIFA.
FIFA confirmed the news to The Times, with a FIFA spokesperson saying: “We can confirm that we have received a claim from the German club Eintracht Frankfurt against English club West Ham United. The matter is still being investigated and consequently we cannot provide any further comments."
The exact reasoning behind the payment not coming through is not disclosed, but the issue is not thought to be serious with the club having the necessary money available and it's currently being dealt with. West Ham's camp is confident that they won't face any sanctions from FIFA.
In regards to matters on the pitch, Haller has failed to live up to his billing, netting just seven times in his 27 Premier League outings. David Moyes' side find themselves deep in a relegation battle, but gave themselves a major boost with their shock 3-2 win over Chelsea last time out.
Haller played no part in that clash and has yet to feature since the league restarted after being sidelined with a hip injury picked up prior to the club's defeat to Wolves.