"His phone has been turned off or the battery has run out,” said police investigator Anssi Köykkä, who’s leading the operation.
Arttu Ollila was last seen leaving his friend’s house at 2pm on Thursday. Police have used dogs, heat-detecting cameras and helicopters in their search, which is being aided by 70 volunteers.
When still switched on, the mobile was traced to a cellphone mast near Arttu’s home. The search is currently focusing on areas near the boy’s home and school.
Arttu is 130cm tall with a sturdy build and blond hair. He was wearing a green jacket and black outdoor pants.
Tips can be phoned in at 07187 48140 or at the emergency number 112.