Raymond Hewlett is alleged to have been staying around an hour's drive from the McCanns' holiday flat in Praia da Luz, Portugal when she vanished on May 3, 2007.
The McCanns' investigation team wants to interview the 64-year-old in the next few days in the hope he can shed some light on her disappearance.
A former soldier who met Hewlett at a campsite in Morocco in May 2007 told the Sunday Mirror he admitted parking a van close to the McCann's complex on several occasions.
Peter Verran, 46, said: "He brought Madeleine up straight away. He said his three-year-old daughter looked like her.
"He was worried that because there had been reports that Madeleine may have been spirited away to Morocco, people might think his child was her. Then he suddenly said, 'Madeleine's not in Morocco'.
"I asked him what he meant and he said he knew Praia Da Luz really well. He knew the Ocean Club complex where the McCanns had been staying.
"He said he'd been there many times and had often parked his van close to the apartment.
"He said he knew the layout of the place, the flat and the restaurant where the McCanns and their friends had been eating when Maddie disappeared.
"He had a lot of detail about the layout. He said there was no way that the child could be taken without the parents seeing. He said they were lying."
This has been reported on Sky News.
I don't doubt him for a minute. He knows the layout, and the last paragraph speaks volumes. I think he is innocent though, because he would have not bothered to say anything to someone if he were involved.
Gerry and Kate may yet be undone The Tapas Nine have some serious confessing to do.