Merseyside Police began investigating footage of Saturday’s FA Cup match at Anfield after complaints were made when an image of the gesture was posted on Twitter.
Police did not identify the man but gave his age and said he was from North Wales. He was detained late Saturday.
A total of 17 people were ejected either before or during Liverpool’s 2-1 win in the rivals’ first meeting since Luis Suarez allegedly abused Evra, who is black, in October.
Suarez is serving an eight-match Football Association ban over the incident and watched Saturday’s game from the stands.
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