An appeal from McCann's parents is to be broadcast on the BBC during Monday's episode of Crimewatch. It will also be shown on German television on Wednesday, at 8:15pm on ZDF, during crime programme Aktion XY...ungelöst.
The two photos show men between the ages of 20 and 40, one with short dark hair and the other a shaved head.
Police believe two of the suspects speak German and could have played a key role in the three-year-old's disappearance in May 2007 from her parents' hotel room in Portugal.
Chief investigator at Scotland Yard Andy Redwood said in a press conference that he hoped the television appeal would help bring forward more information that could push them closer to finding the girl.
“For six years we did not give up our worldwide search for our daughter. Now there is new information, new hope,” the McCanns told Bild newspaper.
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