Police are investigating claims that West Ham supporters threw coins at Frank Lampard following his 200th goal for Chelsea at the weekend.
In a statement, West Ham said:
"West Ham United will be working with Chelsea to investigate the reports of missile throwing during Sunday's game at Stamford Bridge.
Any individual found to have acted in an inappropriate way will have to face the consequences of their actions, including the possibility of a ban from attending future matches."
More top news
Vlogging from her home in London she has become a YouTube sensation, so successful she has just published her first book.
Health union workers were due to walk out on Thursday in a dispute over pay.
Rail services through Farringdon are being delayed again tonight as engineers carrying out safety checks.