West Ham could be stopped from paying CSKA Moscow the next instalment of their transfer fee for Nikola Vlasic.
As reported by The Guardian, the payment may be prevented as a consequence of sanctions imposed by the UK government on Russia following the invasion of Ukraine.
West Ham signed Vlasic last year for £25.7million, with the next instalment of the transfer fee due to be paid in August.
Sanctions could prevent English clubs from being involved in transactions with Russian teams.
If West Ham were unable to make the payment then it remains to be seen what the ramifications will be, with FIFA likely to have to step in and deal with the issue.