Bob Sinkinson: Hundreds of thousands of cartons will be distributed

Jade Bennett, four, and her half sister Hannah, three, disappeared from their home in Cambridgeshire along with their foster parents Jeffrey and Jennifer Bramley.

There have since been possible sightings of them in various parts of England and Ireland.

The frozen food chain Iceland is to print the picture of the two missing foster sisters on milk cartons in the hope that someone will recognise them.

Jade Bennett: Vanished

The tactic has been used in the United States for many years to help trace missing children.

The sisters' mother Jackie Bennett, 24, voluntarily put her daughters in the care of Cambridge social services while she was suffering from a serious psychiatric disorder in 1997.

Detectives in Cambridgeshire believe the Bramleys, who have no children of their own, may have feared that the girls were about to be taken away from them.

Hannah Bennett pictured with her foster mother Jennifer Bramley

Officers believe the foster parents must have meticulously planned their disappearance to have evaded detection for so long.

Mr Bramley is 5ft 6in tall, slightly built with receding ginger hair. His wife is four inches shorter, with dark, medium-length hair and dark eyes.

They are believed to be travelling in a blue Honda Concerto, registration number G152 SHR.

But police believe it is possible they have sold the car and taken on disguises.