The search for Madeleine McCann has been hijacked by her parents' "gigantic propaganda machine", Portuguese police have claimed.

Officers lashed out against Kate and Gerry McCann's slick PR operation after learning they had granted an interview to glossy magazine Vanity Fair, and could even make '2million from a film about their daughter's disappearance.

A source close to the investigation said detectives were furious about the latest publicity, which came as formal requests for the McCanns' friends to be reinterviewed were sent to Britain.

Police are also skeptical about "a surge" of new witnesses traced by the couple's private detective agency, Metodo 3, the Portuguese newspaper Correio da Manha reported.

The unnamed source said: "Who do the McCanns think they are'

"The discovery of new witnesses in the last few weeks have led authorities to believe they are battling against a gigantic propaganda machine.

"The McCanns have some very powerful people on their side - millionaires, celebrities and even politicians."

A second official dismissed the work of the couple's detective agency as "diversion tactics", aimed at distracting police away from the McCanns, who are still official suspects in the case.

He said: "Their tactics are really beginning to annoy us. Whenever a decisive date approaches the company takes a new rabbit out of the hat."

The attacks are a clear indication of the anger that the McCanns' publicity campaign has caused in Portugal, where police investigations are usually carried out in secret.

They came as Gerry McCann revealed he is tortured by guilt that Madeleine's disappearance is his fault.

In an interview with Vanity Fair, he also admitted there was only a "slim" chance his daughter was alive - the closest he has come to conceding the fact.

"I wish I hadn't gone to the tapas bar," Mr McCann told the society magazine. "I wish I'd stayed in the apartment that night. I wish I'd stayed in the room when I checked on her five minutes longer.

"Of course we feel guilty about not having been there and that is just something we have to deal with for the rest of our lives. We live this 24 hours a day."

Mr McCann, 39, gave the interview alone in October, without his wife Kate, after being approached by the magazine.

Vanity Fair also spoke to the couple's friends and family as well as to the other suspect in the case, Robert Murat.

Mr McCann's sister Philomena told the magazine that he had called her on the night Madeleine vanished and sobbed: "It's all my fault, because Kate and I went out to dinner."

Clarence Mitchell, the family's spokesman, said Mr McCann had not been paid by Vanity Fair and had instead requested donations to the fund in return for cooperation with future projects.

He said the Find Madeleine campaign was to take on a "commercial dimension" to keep it in the black. It emerged on Tuesday that the couple could make '2million from a film about Madeleine's disappearance.

Other projects could include a book deal and even TV chat shows which the McCanns have shunned in the past for fear of seeming like celebrities.

The '1.2million fund to finance the search for Madeleine has been halved by the cost of hiring private detectives, running adverts and paying the family's living costs.

Only '600,000 remains and the balance is expected to drop to only '346,000 by April and possibly zero by June.

Scroll down for more ...

In the Vanity Fair interview, Mr McCann, from Rothley in Leicestershire, said: "I know now that, probably, the chances of getting Madeleine back are slim.

"You might never see her again. But still you have the hope. Still."

He told how he sank into a depression after his daughter's disappearance from a resort villa in Praia da Luz, Portugal, on May 3. He said the world then seemed "all black, with maybe tiny points of light".

 

But the consultant cardiologist said he pulled himself out of the "darkest hours" by throwing himself into the campaign to find his daughter, adding: "Grief washes over you - it's like a big wave, mostly I was able to beat it back.

"We can't cry our eyes out every day, because that's not helping. So after three days I picked myself up - quicker than Kate could."

He conceded that his wife remained "fragile" and had struggled to deal with the loss of Madeleine, who vanished a few days before her fourth birthday.

The couple, who are both suspects in their daughter's disappearance, insist she was taken from her bed while they ate dinner with friends nearby.

Scroll down for more...

Portuguese secrecy laws mean they are not allowed to speak directly about the investigation, or the events of May 3.

Mr McCann told Vanity Fair writer Judy Bachrach: "I can't talk to you about the details of what happened.

"I live under threat from the Portuguese - if I do talk - of two years' imprisonment."

But Trish Cameron, Mr McCann's sister, told Vanity Fair of Kate's dramatic reaction when policeman Ricardo Paiva told her she was being made a suspect.

She said Kate screamed at the officer: "Do you honestly believe that I would murder my own child'"

The McCanns were interviewed and formally named as suspects on September 7 and Mrs McCann was allegedly offered a two-year jail sentence if she confessed to accidentally killing Madeleine and hiding her body.

Mrs Cameron said Kate, a 39-year-old family doctor, rejected the deal saying: "I'm not going to f****** lie!"

The couple's psychologist, Alan Pike, who counselled them every day for a fortnight in May, said Mrs McCann was threatened with losing her other children, two-year-old twins Sean and Amelie.

He told Vanity Fair: "The police told her during the interviews that her other two children might be taken away."

Another friend told the magazine that Mrs McCann was tormented about her daughter's welfare, saying she constantly said: "I hope whoever has Madeleine is giving her blankets, is feeding her properly, is keeping her warm."

Jon Corner, another friend interviewed by Vanity Fair, said Mrs McCann told him she was tortured by the idea that she might have glimpsed the abductor.

He said: "She told me 'I wish I could roll back time and go back to the day before Madeleine was abducted. I would slow down time. I'd think: Where are you' Who are you' Who is secretly watching my family' Because someone was watching my family very, very carefully. And taking notes'."

The couple endured a swing in public opinion against them after they were named as suspects and Mr McCann said this was a "bleak" time.

They also lost some of the support they had attracted from politicians, including Gordon Brown, who had telephoned them to pledge his help.

Mr Mitchell said the couple had been offered only a medium-level consular meeting by Downing Street, which they rejected.

In the interview, Mr McCann spoke frankly about how he and his wife employed a "strategy" to keep their daughter's plight in the headlines.

They were criticised in Portugal for circulating pictures of Madeleine and revealing the distinctive fleck in her eye, which police said could have put her life in danger.

He admitted the plan was risky but that "in terms of marketing, it was a good ploy".

Mr McCann said he had considered the plans for a documentary-drama only because it could address issues such as alert systems to help find lost children.

' The third suspect in the Madeleine McCann case broke his eight-month silence yesterday to insist: "I am innocent."

Robert Murat, an expat Briton, has never spoken publicly about the decision of Portuguese police to make him an "arguido" in the case.

But he told Vanity Fair: "All I can say is that I am innocent. There is no way I was at the resort that night. Full stop. I was in my mother's kitchen until 1am. I spent the night at the house."

Relatives of the 34-year-old say he spoke "off the record" to the magazine's writer, Judy Bachrach, while he drove her around Praia da Luz.

They said he was not paid and had not broken Portugal's secrecy laws which ban arguidos and witnesses in criminal cases from speaking about the alleged crimes or the police investigation.

Mr Murat, who has a daughter in Britain from a failed marriage, was named as a suspect last May 14 and his girlfriend, Michaela Walczuch, and her estranged husband, Luis Antonio, were interviewed as witnesses