A VICIOUS thug glassed a bouncer during a horror attack at a city karaoke bar.

He smashed the glass tumbler into the doorman's face as the singing session hit a sour note and his friend was being thrown out of the city centre venue.

Police said the suspects - who are believed to be German - lashed out with the glass and hit the victim as he tried to escort them from Cosmopol for "unruly behaviour".

It happened at the karaoke bar, in Hope Street, at around 1.45am on Saturday, and the pub worker was left with a "serious laceration" on his face.

Officers are now probing the possibility that the two men were tourists, who may now have left the city.

Detectives slammed the attack as "violent and unnecessary" and vowed to find the men responsible.

Police believe karaoke revellers could hold vital clues in the hunt for the attacker.

Detective Constable Shona MacKinnon, who is based at Stewart Street police office, is leading the investigation.

He said: "This was a violent and unnecessary attack which has left a member of staff with a serious injury as a result.

"I would urge anyone who witnessed the incident, or who has information that could assist our inquiries, to contact the criminal investigation department at Glasgow City Centre Police Office."

Both suspects are described as being European, possibly German.

The first man is around 5Ft 11in tall, with dark brown hair, and a slim build. He was wearing a dark jacket with a dark top

His friend is described as being about 6ft 3in tall, bald, of stalky build and between 40 and 45-years-old.

Officers are also carrying out a CCTV trawl in a bid to find out more about the incident.

Police believe the pub would have been busy at the time of the incident, and witnesses have been asked to contact detectives with any information about the vicious attack.

Anyone with information is asked to contact Police Scotland on 101.