Police dogs are helping to search an old railway line in the hunt for a 90-year-old man missing for four days in wintry conditions.

William Ritchie, known as Bill, was last seen by neighbours in the West Road area of Fraserburgh, Aberdeenshire, at about noon on Friday.

A major search has been underway to find Mr Ritchie, who was reported missing on Sunday.

Specialist search officers with assistance from Police Scotland’s dog unit are carrying out a search along the 11-mile stretch of old railway line from Fraserburgh to Strichen as a potential route the pensioner may have taken.

Inspector Kevin Goldie said: “Another night has passed without anyone seeing or hearing from Bill which means our concerns for him are growing.

“Bill has been known to be a keen walker in the past and regularly took a route round Fraserburgh covering West Road, Strichen Road, Boothby Road and Watermill Road.

“On occasions he has been known to walk as far as Memsie and Strichen but has been keeping closer to home recently.

“Searches will continue today to ensure a possible route Bill might have taken is thoroughly searched while we make the most of daylight hours.”

Mr Ritchie is described as being around 5ft7, of slim build, with short grey hair.

He usually wears a 3/4 length black jacket although it is not known what he is wearing at the moment.

Anyone with information is asked to contact police on 101 quoting incident no. 2549 of Jan 14.

Inspector Goldie added: “I would ask anyone who has seen Bill in the last week to please get in touch as our enquiries continue. He regularly shops at Asda and the local Co-op and attends at the post office at Mid Street.

“He appears to be a well-known face in the Fraserburgh area and we would ask anyone with information about his movements in the past week to please get in touch.”