A man was knocked unconscious after a street attack in Glasgow city centre.

Police said the 42-year-old victim was discovered lying in Cadogan Street, at West Campbell Street.

A member of the public raised the alarm around 9.15pm on Sunday but he left before paramedics arrived.

Detectives are keen to trace him as part of the serious assault probe.

The victim was taken to Glasgow Royal Infirmary where he is undergoing treatment for facial injuries.

Detective Constable Nicol McPherson said: "The man who called the ambulance left the scene before it arrived and took the injured man to hospital, so we are keen to speak to him about what he may have seen or knows about what happened.

"Officers have been checking CCTV in the area and we know that Cadogan Street at West Campbell Street can be quite busy around that time of night.

"There is a local soup kitchen not far from where the attack took place so it is possible that someone there saw the attack and could help our investigation."

Detective Constable McPherson urged anyone with information to contact Glasgow City Centre CID via 101, quoting incident number 4103 of Sunday 9 September 2018 or Crimestoppers, anonymously, on 0800 555 111.