The Met Police said the search is being conducted on the river following a review of CCTV in the area that indicates that Harvey may have entered the water near the Golden Jubilee Bridge.
At this stage of the investigation there is nothing to suggest that there is any third party involvement.
Detective Chief Inspector Lucy O’Connor, from Central South Safeguarding Unit, said: “We are doing all we can to find Harvey, and working closely with our colleagues in the Marine Policing Unit.
“We are keeping Harvey’s family fully informed of any developments; and the thoughts of my colleagues and I are with them at this distressing time. We would also ask that media avoid any speculation while the enquiry continues.”
Anyone with information is asked to call 101 or tweet @MetCC. Please quote CAD 3134/18DEC21.