This bizarre sketch captures why the police investigation into the abduction of Madeleine McCann has been so savagely condemned.

Officers have not released any photofit or artist's impression of the suspected abductor.

But they have, apparently, shown a sketch like this to residents in Praia da Luz.

This bizarre sketch captures why the police investigation into the abduction of Madeleine McCann has been so savagely condemned.

Officers have not released any photofit or artist's impression of the suspected abductor.

But they have, apparently, shown a sketch like this to residents in Praia da Luz.

One of them was Simon Russell, 40, runs a video store and Internet cafe in the former fishing village.

"I smiled when they showed it to me. What else could you do?" he said.

He said the sketch was so simple it was easy for him to recreate, and it is Mr Russell's drawing that is used here.

He described it as looking like "an egg with a side parting".

The fact that such a virtually useless image is being used underlines claims that the Portuguese police are getting increasingly desperate.

"They have got absolutely nothing and are following up lines of inquiry which are barely credible," said a British police source familiar with the inquiry.

Last night there were signs of tension between the Portuguese police and the British specialists who have flown out to help them.

The local force accepted an offer for two "Cracker"-style experts from the UK's Child Exploitation On Line Protection Centre to assist with the investigation.

They arrived on Tuesday but a source close to the Portuguese detective leading the hunt said: "The British specialists aren't being received very well by the Judicial Police.

"There is quite a bit of friction there. The English guys have come out to make profiles of the kidnapper but the Portuguese officers are not entirely happy with the way their investigation is being taken over.'"

Various Portuguese papers, quoting anonymous police sources, have referred to a variety of suspects police are said to be interested in.

One is said to be a man believed to be Portuguese or Brazilian with thick dark hair and a side parting, wearing a dark jacket and white trousers.

Another is of a man thought to be northern European of about 6ft tall, medium built with a dark tan and a centre parting - and said to have been seen repeatedly using a public phone box in Praia da Luz shortly before Madeleine disappeared.

But no photofits or e-fits have been published by the police, on the grounds it is against Portuguese law to reveal any information about their inquiry.

There were also claims last night that Portugal's Judicial Police, the equivalent of Britain's CID, even held back from showing images of suspects to uniformed officers in the region.

A uniformed police source said he and his colleagues were not allowed to see sketches of suspects until Monday - four days after Madeleine's disappearance.

The source told a paper that he felt it was extremely counterproductive to have that portrait and not to pass it to other police forces or even publish it more widely.

"It is time to set aside petty pride and rivalry between police forces,! he is quoted as saying.

Police claim they have examined 500 apartments in the area, followed up 350 different leads, interviewed 100 people and taken hundreds more calls since Madeleine disappeared - but there has not been a single positive sighting and there is no evidence that officers have a clear suspect in mind.

The Portuguese inquiry has been boosted this week by assistance from Britain, with officers sent over including Chief Inspector Graham Hill from Surrey Police, who has been involved with the hunt for the killer of Milly Dowler, 13, who went missing from Walton on Thames in March 2002 and whose body was found six months later.