Detectives want to speak to three people after trouble broke out between rival football fans in Upper Bangor.
CCTV pictures have been released of two men and a woman after a police cordon was broken on Holyhead Road at around 6.30pm on Saturday 26th January.
A police officer was injured in the disturbance, which occurred before the Welsh Cup derby between Bangor City and Caernarfon Town at Nantporth. Around 2,500 were at the fourth round tie, which Caernarfon won 2-1.
At the time of the incident, Superintendent Richie Green said the disorder was brought under quickly, but his injured colleague was taken to hospital.
Another officer was injured on the same night in a separate incident elsewhere in the city. Ten people were held in custody, but not all of the arrests were linked to the match.
PC Leslie Ellis said on Thursday: “As part of our ongoing investigation, we would like to identify the woman and two men in the CCTV stills.”
Anyone with information should contact Bangor police station on 101, quoting reference no. 19100027984, or Crimestoppers anonymously on 0800 555 111.