Leeds United and Barnsley have responded to reports of fighting in the stand during the Championship fixture between the two sides on Sunday.
The trouble broke out during the second half of the tie at Oakwell, which kicked off at 12.30pm.
Fans appeared to be seen clashing with stewards, though it is unclear what caused the fighting.
Following the tie, Leeds boss Marcelo Bielsa commented on the incident.
He said: "I feel pity that something like that happened, but I didn't see it.”
Now the clubs have responded. An club spokesperson said: "Leeds United and Barnsley Football Club are greatly disappointed by reports of violence at yesterday’s game and will be working together to assess the matter."
United aren't in action again until Saturday's lunchtime kick-off against Derby County.
The clash will be the first time the sides have met since the painful play-off defeat in May.
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