Sunderland chairman Niall Quinn has revealed the club has been working to address the causes of the trouble which marred the derby victory over Newcastle.
Rival fans clashed on the final whistle after a pitch invasion by some home supporters, while Magpies keeper Shay Given had earlier been confronted by two men in the wake of Kieran Richardson's winning goal.
Writing in his programme notes ahead of Saturday's Barclays Premier League clash with Portsmouth, Quinn said: "I haven't spoken publicly about the work we have been doing since the Newcastle game, but I want to assure all of you that we have been working hard to produce a comprehensive report, not to apportion blame, but to make sure that we work together with the police and our own stewards to ensure that we co-operate successfully."
He added: "I know that whatever problems there were at the end were caused by a variety of reasons, and I understand the emotions of the day.
"But as thrilled and ecstatic as we were with the result, we have to work collectively to maintain the fantastic atmosphere we are renowned for, while always appreciating that the safety of every single person in the stadium is paramount."
Manager Roy Keane played down the trouble after the game, but later admitted fans running on to the pitch was unacceptable.
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