Work is underway to publicise a missing person appeal for Mikaeel Kunar on digital billboards across the UK, the charity Missing People has confirmed.
The adverts are expected to go on display in areas such as train stations, shopping centres, as well as near motorways and at bus shelters.
Police are "deeply concerned" for the welfare of the three-year-old as the search enters its second day.
A timeline of events surrounding the disappearance of three-year-old Mikaeel Kular.
What tools and techniques will police be deploying in their effort to reunite Edinburgh toddler Mikaeel Kular with his family?
Hundreds of people have gathered to join the search for a missing three-year-old boy who was last seen on Wednesday night.