Police searching for missing 73-year-old Stephen Gibson are continuing their searches this evening with the help of nine, specially trained search and rescue dogs. The dogs work with volunteer search and rescue teams and are travelling from across the country to assist with the search.
Officers from North Yorkshire Police will also be using thermal imaging cameras to search for Mr Gibson.
He was last seen at around 4pm walking along a path between Lastingham and the Chimney Bank as the fog and darkness descended.
His fellow walkers raised the alarm at 7pm when he did not return to his vehicle.
Police and search and rescue teams have been searching overnight with air support from the National Police Air Service helicopter. Further searches continued throughout Thursday with assistance from search and rescue volunteers and RAF air support.
Inspector Mike Fenton of North Yorkshire Police, said:
Mr Gibson is a regular walker, is very fit and knows the area well, however we are growing concerned for his safety and fear he may have got into difficulty or has been injured. He did not have any food with him or overnight equipment.
If anyone has seen a man matching his description in the areas around Lastingham, Rosedale and Hutton le Hole, or has given him shelter overnight, we urge you to contact the police.
Mr Gibson, who is from Terrington near Malton, is described as white, around 5ft 10in, with blue eyes, grey, balding hair and wears glasses. He was wearing a blue and green waterproof jacket, a quilted waistcoat, breeches, boots and a tweed cap.
Anyone with any information is asked to contact North Yorkshire Police on 101 and pass information to the Force Control Room.