UPDATE: Liam has since been traced safe and well. Click here for more information

An appeal has gone out to help police trace a Lanarkshire teenager.

Liam Southby, 15, was visiting a relative in St Andrews and failed to return to his home in Airdrie, North Lanarkshire, four days ago.

He was last seen in the early hours of Monday and has not been in contact with friends or family.

READ MORE: 'Very silly' fan gave false name to watch Rangers Greenock Morton game

The teenager is known to travel by bus and has connections in Dundee, Edinburgh and Airdrie as well as Fife.

He is described as white, slim, 5ft 9in, with blue eyes and short dark brown hair, which is shorter than in his photograph, above.