Police are appealing for help to find a man who has gone missing from a hotel in the Blue Mountains, west of Sydney.

Gary Tweddle, from Cremorne on Sydney's north shore, left the Fairmont Resort at Leura in the early hours of this morning and has not been seen since.

Police say the 23-year-old's disappearance is totally out of character.

Officers and local volunteers are searching an area of bushland near where he was last seen.

Mr Tweddle is described as 165-170cm tall, medium build with brown eyes and brown hair.

He is thought to be wearing blue jeans, black jacket and checked shirt.

Anyone with information on his whereabouts is urged to call Crime Stoppers on 1800 333 000.