A Portuguese man has come forward to report a possible sighting of Madeleine McCann the day after she disappeared, it has been revealed.

Carlos Moreira, 65, saw a young blonde girl wearing pyjamas like those of the missing British child in the back of a van on May 4, 2007.

But he only contacted the private investigation team employed by Madeleine's parents, Kate and Gerry McCann, last week.

It is understood that he did not think the information was relevant until learning in a recent TV programme that Portuguese police did not mount roadblocks following the little girl's disappearance.

Madeleine was nearly four when she went missing from her family's holiday flat in Praia da Luz in the Algarve on the night of May 3, 2007, as her parents dined with friends nearby. 

At about 8am the next morning Mr Moreira saw a young girl lying at an angle in the back of a white van at a roadside snack bar near the Portuguese capital Lisbon, some 170 miles to the north. He said she was with a man and a woman.

It is understood Mr Moreira was not certain that he saw Madeleine, but recalled that the girl was wearing pink and yellow pyjamas similar to the ones the missing child had on when she vanished.

He told a newspaper: "When the van door was opened, she did not wake up, as if she was drugged. This girl was blonde and looked around four."

McCann family spokesman Clarence Mitchell said: "I can confirm that Mr Moreira has been spoken to by the private investigators currently searching for Madeleine.

"I cannot go into any further detail for operational reasons. He has done absolutely the right thing in coming forward with his information despite it being so long after the event."