The family snap shows Madeleine and younger twins Sean and Amelie playing with their father Gerry McCann while on holiday in Portugal.

Madeleine's parents are hoping that the picture could help jog the memory of anyone who saw anything suspicious at the time of her abduction.

She was taken from the family's apartment in the Algarve resort of Praia da Luz on the night of May 3.

Portuguese police are following up reports that a man was seen near the apartment possibly carrying a small child.

The picture was released shortly after it was revealed that Gerry and Kate McCann are to meet the Pope.

The couple, who are both Roman Catholics, could meet Benedict XVI at a general audience at the Vatican as early as Wednesday.

Meanwhile, the woman who may haveseen Madeleine being carried off in the arms of a mystery man is wracked with guilt that she did nothing to stop him.

A close friend of Kate and Gerry McCann, she believes she saw a blonde girl wearing "distinguishable" pyjamas and wrapped in a blanket.

She thought it odd at the time but only realised later that it might have been Madeleine.

Described by police sources as the "principal witness" in the case, the woman has now returned to the UK and is brooding over what she saw.

Details of the sighting came as hundreds of calls were made to police about the description of a white man aged between 35 and 40 seen holding what was thought to be a child on the night Madeleine disappeared.