About 300 Newcastle supporters travelled to Wearside for a Premier League International Cup quarter-final against Sunderland.
Several seats were broken during the match, which the Magpies went on to win on penalties.
This video sent to us captures Newcastle fans chanting and waving around parts of seats.
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In the clip, they are heard singing 'the Geordie boys are taking the ****'.
There is currently no evidence that the fans in the video were responsible for the damage
Pictures taken following the game clearly showed seats missing in the South Stand of the Stadium of Light.
A tweet sent by one Newcastle fan after the match said that he had one of the seats.
He later tweeted that he had found the seat on the Metro on his way home, and advised the club to call the train operator's lost and found department.
The seats were broken after Lynden Gooch put Sunderland 2-1 ahead in the second half of the match.
Newcastle's Callum Roberts equalised in stoppage time to force the game into extra-time, and they then went on to win 11-10 on penalties.
There was a small police presence inside the stadium for the game, which was the first reserve derby in four years.
A statement from Newcastle United said: "Newcastle United is aware of the unacceptable behaviour of a number of its supporters who attended last night’s Under-23s match against Sunderland AFC at the Stadium of Light.
"The club is very disappointed to hear of the actions of a small group of individuals and will do everything it can to help the police identify those responsible and hold them to account."
Chief Superintendent Sarah Pitt, of Northumbria Police, said: “Reports of minor disorder and damage to the stadium are being looked into by police and officers are carrying out enquiries and reviewing CCTV to identify those involved.”
Anyone with any information, or was involved themselves, should contact police on 101 and quote reference number 648 07/03/18.