Sunderland owner Kyril Louis-Dreyfus says he was “disgusted” after a bar at the Stadium of Light was redecorated with Newcastle slogans.
The Black Cats Bar, to be used by away fans, was furnished with the signage for Saturday’s FA Cup third-round tie.
“I regret to have let you down,” said Louis-Dreyfus, 27.
The slogans, which have since been removed after Sunderland admitted a “serious error in judgement”, included “keep the black and white flying high”.
“I would like to apologise to everyone associated with Sunderland AFC for the events that have unfolded today,” added Frenchman Louis-Dreyfus.
“Like our supporters I was disgusted and hurt by the pictures circulating online of the inappropriate signs that have now been ripped down.
“I take full responsibility for every decision that is taken by the employees of our club and you have my word that I will personally make sure that we make the necessary changes required to improved because it is clear there are many areas where we need to be better.”
Further images of the bar, which is being used for hospitality for Newcastle supporters, showed signs including “we are united” and “cheer up Peter Reid” – a reference to a chant sung by Magpies fans about the former Sunderland manager.
In an earlier statement after widespread criticism from fans online, Sunderland said the club “acknowledges that a serious error in judgement was made in relation to Black Cats Bar earlier this afternoon”.
“We apologise to our fans for the understandable concern they have fairly voiced in response and this sentiment is shared by the club’s ownership group and board of directors, who have requested an immediate review is undertaken to determine how this process unfolded,” the club added.
‘This will be mentioned in 50 years’ time’
Speaking to BBC Radio Newcastle, former Sunderland striker Marco Gabbiadini described the error as “embarrassing”.
“We’ve got a group who’ve taken over the club who you would think, after the last lot we’ve had, would have a bit more knowledge of how football works,” he said.
“There are people from the region on the board. The owner, his club was involved in one of the biggest rivalries in French football with his family’s club, and we’ve opened ourselves up to this. I don’t believe it if I’m honest.
“It’s embarrassing. This will be mentioned by Newcastle fans in 50 years’ time.”