Did this man snatch Madeleine?

(CNN) -- The parents of missing toddler Madeleine McCann have released an artist's impression of a man they believe took their daughter.

The sketch is based on an account given by the couple's friend Jane Tanner, who was eating with Jerry and Kate McCann on the evening that the British girl was taken from the family's Portuguese holiday apartment.

Tanner has said that she saw the man walking away from the area of the McCann's apartment but at the time did not realize the relevance.

The impression, which was released yesterday, shows a man of southern European or Mediterranean appearance walking while cradling a child.

The abductor is 5ft 6in (1.7m) tall, of slim build and aged between 35 and 40. He has straggly or greasy dark hair and is wearing a brown or maroon top and beige chinos.

He is shown carrying a child, whose legs, clothed in the same pyjama bottoms as Madeleine's, can be seen dangling from his arms.

The artist has left blank certain details, such as the face, of which Tanner was uncertain.

Clarence Mitchell, spokesman for the McCanns, said: "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.

"We believe this was Madeleine being carried away by a man from the apartment, so we place great importance on having these pictures produced."

He added that Portuguese police had given "tacit approval" to the drawing.

It is believed that the impression was drawn by an unnamed FBI-trained forensic artist, commissioned by private detectives working on behalf of the couple.

Earlier in the week the couple launched a confidential 24-hour phone line, manned by private detectives and aimed at Spain, Portugal and north Africa, to encourage further information about their daughter's disappearance in May.

Mitchell said the response so far has been "very good". The number to call is (34) 902 300 213. E-mail to a friend