The Clarence Mitchell, the McCanns' spokesman, said: "Kate and Gerry remain very grateful to the Met for the work they are doing in liaison with the Portuguese authorities.
"Their forthcoming appearance on Crimewatch is an important stage in that ongoing process. Naturally, they hope it will lead to information that will provide the breakthrough to finding Madeleine."
Since launching its own investigation, Scotland Yard says 41 people of interest have been identified, including 15 UK nationals, up from 38 people of interest including 12 UK nationals established in July.
Detectives have issued 31 international letters of request (ILOR) to mostly European countries in relation to some of the persons of interest as well as accessing phone records.