Sunderland have apologised for a "serious error in judgement" that saw a stadium bar redecorated with slogans backing bitter rivals Newcastle.

The Stadium of Light's Black Cats Bar, which will host Toon fans for the two sides' FA Cup clash on Saturday lunchtime, had been furnished with special signage for the occasion.

However, leaked photos showing slogans such as "keep the black and white flying high" and "we are United" on display sparked a furious reaction from Sunderland supporters on social media.

Shortly after the images begun to circulate, the club released a statement confirming they would be removing the banners with immediate effect.

It said: "Sunderland AFC 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.

"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.

"A direct decision has also been taken by the ownership group and board of directors to return the space to its original state and we once again apologise to our supporters that this was not addressed sooner."

Saturday's encounter marks the first Tyne-Wear derby in almost eight years, which was the last time both teams were in the Premier League together.

Though the Black Cats will be huge underdogs against their wealthy rivals, they are on a run of nine head-to-head meetings without defeat, winning six of the last seven.