Portuguese police investigating the abduction of Madeleine McCann are hunting for a balding man who is believed to have been seen dragging a girl to a marina in a town close to where she disappeared.

Detectives have not identified the man but have said that he is a suspect in the kidnapping of Madeleine from a holiday apartment on the Algarve on Thursday night.

Detectives have found evidence showing that the British girl was abducted, but have few clues as to who took her or where she is being held.

A police artist’s impression of a balding man who was seen with a blonde girl similar to Madeleine shows just the back of his head. He is described as being white, 5ft 11in and is understood to have been wearing white trousers.

The man is believed to have been seen dragging the girl on a road leading to a marina in the town of Lagos, about 5 miles (8km) from Praia da Luz. Another witness is reported to have seen a girl struggling in the back of a car on a road leading from Praia da Luz.

The Times has learnt that the police are preparing to scale back their searches in Praia da Luz and the surrounding area. Senior officers believe that they have searched every possible place for Madeleine and are planning to divert search teams to other places in the Algarve.

Detectives still believe that she is alive but think that she has been removed from the immediate area.

Guilhermino Encarnacao, director of the Policia Judiciaria in the Faro region, said: “There is evidence of a kidnapping. In Portugal, according to the law, kidnapping can be for ransom or can be if someone holds a person for sexual abuse. We believe that she is still alive and is still in the country. She is probably in the Algarve.”

He confirmed that one line of inquiry was the report of a couple seen walking along a road with a child.

A British officer from the Serious and Organised Crime Agency is in Portugal and working closely with local detectives by providing expert advice on forensic science and search techniques and investigations into child abductions.

Hundreds of tourists and ex-pats from across the Algarve and southern Spain have joined police in searching Praia da Luz and surrounding areas over the weekend. The search area was yesterday extended to 5 miles from the Ocean Club resort from where Madeleine, 3, was taken.

Bryan Kennedy, Madeleine’s great-uncle, said: “Obviously as the days go by it gets harder, because you start by hoping for the best and then begin to start fearing for the worst.”

He defended the decision of Madeleine’s parents, Gerry and Kate, to leave their children alone in a rented holiday apartment while they had dinner at a restaurant a few yards away on the Mark Warner Ocean Club resort. Mr Kennedy, a retired head teacher, said: “They were in a restaurant that was part of the holiday complex and, like parents do, kept popping back to make sure the children were safe.”

Police at road blocks have been stopping and searching cars on the main roads in the region. However, it emerged yesterday that the border crossing into Spain, about 90 minutes’ drive away, had not been informed of Madeleine’s disappearance for at least ten hours.

The girl’s relatives in Britain have complained that the Portuguese police have been uncommunicative and said that they had “played down” the kidnapping. However, Mr and Mrs McCann thanked the police on Saturday night. Mr McCann said: “We would like to thank everyone here in Portugal, the UK and elsewhere for all your support.”

The founder of an international child protection group claimed yesterday that corruption and indifference among the Portuguese authorities hampered the country’s investigation of paedophiles and child traffickers. Homayra Sellier, of Innocence in Danger, which was launched in 1999 on Unesco’s initiative, speculated that Madeleine was taken either by an individual with mental health problems or by an organised child-trafficking gang.

“These people are criminals – somebody who did what they did with Madeleine is beyond being a paedophile,” she said.

The head of the company that runs the resort where Madeleine went missing insisted today that her abduction was a “one-off”. David Hopkins, managing director of Mark Warner, said: “In all the time that we’ve been operating, an incident like this has never happened.”

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