The parents of missing British girl Madeleine McCann on Thursday released an artist's impression of the man they believe abducted their daughter.

The sketches depict a man with shoulder-length dark hair, wearing a brown or maroon top and beige trousers walking with a pajama-clad child in his arms.

They are based on a description of a man seen walking with a child by a friend of Kate and Gerry McCann on the night Madeleine disappeared from the family's Portuguese holiday home on May 3.

The family's spokesman, Clarence Mitchell, said the images were commissioned by private detectives hired by the McCanns and released with the "tacit approval" of Portuguese police.

Mitchell said the suspect was described as southern European or Mediterranean in appearance, about 35 to 40 years old, 5 foot 6 inches (1.7 meters) tall and of slim build.

"This is another important phase of our investigation into Madeleine's abduction and we hope that this picture will be a very important reminder to anyone who was in the area on that night who may have seen this man," Mitchell said.

"We believe that this was Madeleine being carried away by a man from the apartment, so we place great importance on having these pictures produced. Anyone who knows this man should contact our confidential phone line immediately."

Madeleine disappeared from her family's holiday apartment during a vacation in Portugal's Algarve region, a few days before her fourth birthday. Despite a high-profile international campaign led by her parents, she has not been found.

Portuguese police have named a British man, Robert Murat, and Madeleine's parents as formal suspects, but have not laid any charges. Kate and Gerry McCann, who strongly deny involvement, have returned to their home in Britain.

They said in an interview broadcast Wednesday that they believed their daughter was still alive.

"I suppose it's a feeling but I feel, as Madeleine's mummy, I feel in my heart really that she's there," Kate McCann told Spain's Antena 3 television. "I don't believe Madeleine has been taken away from us permanently."