Facial recognition software used to find victims of online abuse in paedophile websites is being used by detectives searching for Madeleine McCann to see if there are any images of her online.

The software searches through hundreds of thousands of images to get an exact match. If a picture of the three-year-old does appear then officers hope they will be able to enlarge the picture for clues to her whereabouts.

CEOP, Britain’s elite anti-paedophile unit, who lead the way in this technology, says it has given Portuguese detectives “a full range of expertise and resources for every possible avenue of investigation”.

Although the Child Exploitation and Online Protection (CEOP) Centre will not comment on the exact nature of the “expertise and resources”, Times Online has been told that officers have “almost certainly” taken a family picture of Madeleine and scanned it in to the database to find out if there are any images of her online.

Officers in Portugal are said to be working on the assumption that the girl was abducted “to order” by an international paedophile network.

Paedophiles use the internet to exchange sexually explicit images of children, often within minutes of grabbing a victim.

John Carr, an internet child safety expert who works closely with CEOP, said that the software had identified hundreds of children.

“CEOP are the global leader in this type of technology and it saves a huge amount of police time. Officers will almost certainly have taken a picture of Madeleine from her family and scanned it into the database to see if any images of her have turned up.

“It would be surprising if they were not doing this.”

Mr Carr said that the whole point of the technology is to find where the children are being held.

“One of the problems is police cannot do anything until they know what jurisdiction the child is in and the only way to do this is to find a clue in the image as to where they are.”

As an example he told how British officers tracked down a father abusing his daughter from an image. An unusual cornice on the ceiling and a box of tools led police to the father with the help of an architectural historian, who pinpointed the Edwardian era design to six large houses in a certain area of the country.

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