A young woman was allegedly raped in a Layton flat.
The incident was reported in the early hours of July 9.
Police want to trace 18-year-old Alex McMahon, from Liverpool, in connection with their investigation. He has links to Blackpool, Wallasey and Salford.
Anyone with information is asked to call (01253) 604112, or email firstname.lastname@example.org .uk quoting the reference number WA1815873.