Detectives investigating the rape of a woman in Huddersfield town centre on June 11 have released CCTV stills of a group of men they want to trace.
The incident happened at 3am on Victoria Lane near the Yorkshire Linen Shop.
A 20-year-old man was arrested on suspicion of rape and released pending further enquiries.
Officers are investigating the incident and are keen to trace the men pictured as they may hold vital information about what happened.
Det Insp Seth Robinson of Kirklees Safeguarding, said: “This is a serious sexual assault and we are appealing for any witnesses to come forward.
“We are keen to speak to the men pictured as potential witnesses.”
Ring 101 quoting Ref 13170264565 if you recognise the men or have any information to offer.