Police had to separate West Ham and Middlesbrough fans after they clashed during disturbances outside the Hammers' new London Stadium.
Officers had to intervene when violence flared in the Olympic Park following Saturday's 1-1 draw between the two Premier League clubs.
Police escorted Middlesbrough fans away from the stadium while cordoning off some West Ham supporters.
The trouble followed recent crowd disturbances inside the stadium.
At the first Premier League match at the venue - against Bournemouth on 21 August - some fans arrived with tickets for seats that did not exist, while fighting broke out between rival supporters outside the stadium.
West Ham confirmed that 10 fans were ejected from the stadium during the 4-2 defeat by Watford last month.
Some of the disturbances inside the ground are believed to be over persistent standing during matches.
The club asked E20, which owns the club's London Stadium home, to ensure there is a police presence in the ground after recent trouble.
But the Metropolitan Police turned down the request because the £700m ground does not have a "satisfactory" radio system.
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