A £12m investigation of the disappearance of Madeleine McCann has been granted an extra £154,000 because detectives are hunting a “person of significance”.

A source close to Operation Grange — Scotland Yard’s six-year search for Madeleine — has said finding the person is one of the “critical lines of inquiry” that police hope may help to solve the mystery. Madeleine, who was then three, disappeared in May 2007 while on holiday with her family in Portugal.

Last week the Home Office announced the funding that will keep four detectives on the investigation until the end of March next year. The source said: “It is as much to rule the person out of the inquiry as anything else.”

Madeleine McCann, then three, vanished in May 2007 while on holiday with her family in Portugal GETTY IMAGES

The Portuguese investigation of Madeleine’s disappearance was criticised