An 18-year-old man has been detained after a 22-year-old woman was sexually assaulted in Aberdeen city centre.
It happened near to The Green, at the bottom of the steps leading from Union Street, between 3am and 4am this morning.
Police were called out at 11.30am, with the area to the side of the staircase taped off.
It is understood staff from the criminal investigation department have also been in attendance.
Officers are appealing for witnesses.
Detective Inspector Stewart Drummond said: “Our enquiries are ongoing to establish the full circumstances and we are following a positive line of enquiry.
“I would also ask anyone who was in the area of The Green or Union Street between 3am and 4am to come forward.
“Anyone with information that could assist our investigation is asked to call Police Scotland on 101 quoting reference 924 of 5 November, or Crimestoppers on 0800 555 111 if you wish to remain anonymous.”