Mass violence between rival football fans that saw a man stabbed was caused by "a small number of supporters" intent on causing trouble, the officer in charge of policing the match said today.
Thirteen people were arrested after clashes between West Ham and Millwall fans inside and outside Upton Park, in east London, last night.
Chief Superintendent Steve Wisbey said: "Police worked closely with West Ham Football Club, British Transport Police and the local authority to minimise disorder.
"Officers responded swiftly whilst missiles were being thrown as they tried to separate fans outside the ground after the match.
"Incidents of this nature at a match are thankfully rare, but it would appear that a small number of supporters were intent on causing a confrontation."