Clarence Mitchell told Sky News he was sceptical about claims made by a private investigator that Madeleine was abducted by an international paedophile gang.
The Angolan-born man and nightclub bouncer who made the claims also said he was forced to flee for his life when the group became aware of his interest.
Madeleine was
nearly four when she disappeared from her family's
holiday
apartment in
Praia da Luz on May 3, 2007.
"We should stress a note of caution here. These are claims that have been made to Spanish police, we understand," said Mr Mitchell.
"If this man has any credible information about Madeleine, he has done the right thing in the first instance by going to the police.
"But of course this information has to be investigated to establish if there is any truth or not."
