Thousands of copies of a Manchester United fanzine, which featured a "potentially offensive image", were seized by police before today's match against Liverpool.
The edition of Red Issue included a spoof poster of a Ku Klux Klan hood along with the words "LFC" and "Suarez is Innocent", it was reported.
Its publication follows the on-going race row involving Liverpool striker Luis Suarez, who was given an eight-match ban for racially abusing United defender Patrice Evra.
Many fans took to Twitter to post images of the fanzine's spoof and voice support and outrage over the publication's move and the police's response.
The tensions were mirrored on the pitch when Suarez refused to shake hands with the United captain before the kick off.
Evra did not accept that and attempted to grab Suarez's arm to complete the formalities, but the striker shrugged him off.
Greater Manchester Police (GMP) said they will take "appropriate action" against anyone found selling the offending edition of Red Issue or displaying it in public.
One arrest has already been made, the force said, in connection with the sale of T-shirts outside Old Trafford which had been "deemed offensive".
Match commander Chief Superintendent Mark Roberts said: "Shortly before kick-off we were made aware that a Manchester United supporters' fanzine being sold outside Old Trafford featured a potentially offensive image.
"Officers are now seizing the fanzines and in consultation with the Crown Prosecution Service we will take appropriate action against anyone either found selling this particular fanzine or provocatively displaying the image in public.
"Officers have also been made aware of a T-shirt on sale outside the ground that is also deemed to be offensive. We are also seizing these items and anyone found wearing one will be required to remove it and hand it to police.
"At this stage we have arrested one man in relation to the T-shirts on suspicion of a racially-aggravated public order offence and we will be continuing to work with the clubs to minimise the impact of the image, which we consider to be offensive.
"I have taken this course of action as both items are potentially offensive and we cannot be in a situation where hundreds or thousands of people were displaying offensive images at a football match. The consequences of taking no action could have resulted in public order incidents inside or outside the ground."
Nobody from Red Issue was available for comment.