Volunteers have joined a police helicopter and dog unit in the search for a missing walker.

Graham Johnstone, 70, was last seen leaving his home in Whitehill Crescent, Annbank, South Ayrshire, at about 10.40am on New Year's Day.

His family contacted police when he failed to return.

Mr Johnstone is a keen walker on local routes and air and foot searches have been carried out around the Auchincruive Estate, Oswald Bridge, Gadgirth and the Mossblown area.

Police said volunteers have been searching walkways with specialist officers, a Police Scotland dog unit and a rescue helicopter.

He was wearing a black zipped top, beige trousers, and a fawn cardigan. He may also have had a hat with him.

An unconfirmed sighting at around 11.45am near Oswald Bridge was reported by a couple and police have been focusing on that area.

A force spokesman said: "The man seen by the couple yesterday had similar clothing to Mr Johnstone's, was wearing walking boots and carrying what may have been an olive green coloured hat or balaclava.

"If this description matches you and you were in and around the Oswald Bridge area around 11.45am yesterday, then please contact police. If the sighting was not Mr Johnstone it's important for police to rule it out.

"Air and foot searches have also been carried out around the Auchincruive Estate, Oswald Bridge area, Gadgirth area and up to the Mossblown area.

"If anyone has seen Mr Johnstone or has any information or knowledge as to his whereabouts, please contact officers at Ayr Police Office on 101."