Portuguese police have dismissed up to four potential Madeleine McCann leads in the past week by telling informers: 'The case is closed, she is dead.'

All the witnesses who came forward offering information about the missing youngster were waved away by indifferent officers in the Algarve.

The revelation was described as a 'disgrace' by friends of Kate and Gerry McCann, who are spearheading a renewed appeal to find their daughter two years after she vanished in Portugal.

Yesterday two private detectives employed by the couple were rebuffed as they tried to question paedophile Raymond Hewlett in his hospital bed in Germany.

Former soldier Hewlett, 62, who was living in the Algarve when Madeleine went missing and has a history of sex attacks on girls, hid in his room and refused to see the pair.

Hewlett, who has cancer, is one of several fresh leads that have flooded in to investigators in the past few weeks.

The McCanns are privately furious that the Portuguese police - who in theory are still in charge of the inquiry - have refused to accept new tip-offs.

A source close to the investigation said: 'In the last week, three or four people have approached the Portuguese police with information, and they were told not to worry them because the case was closed and she is dead.'

It is understood these people later gave their information directly to the McCanns' private detectives.

But the source said: 'What if there are other people who tried to give information and then simply gave up when they were sent away? They could have been squandering potentially significant new leads.'

Although Portuguese prosecutors announced last year they were shelving the Madeleine case, Leicestershire Police still refer new leads to them and claim the Portuguese are still in charge of the inquiry.

A friend of the McCanns - both doctors from Rothley, Leicestershire - said: 'It's a disgrace frankly, it's beyond frustrating. It is exactly the attitude that we have been up against for months.

'They closed the inquiry and were not prepared to lift a finger.'

Two private detectives, former Detective Inspector Dave Edgar and former Detective Sergeant Arthur Cowley, employed by the McCanns flew to Aachen in Germany on Sunday night in an attempt to question Hewlett.

They spent ten minutes talking to his German wife Marianna Schmuker in her council apartment in the city.

But when they visited the hospital yesterday, Hewlett - who has spent much of his life in jail or on the run from police - made it plain he had no intention of cooperating.

Mr Edgar said: 'If he's got nothing to hide, he should speak to us. It is a matter of urgency because of his medical condition.' 

The two investigators also came up against a wall of German bureaucracy.

Because Hewlett is not suspected of a crime in Germany, the authorities cannot compel him to cooperate - unless they receive a request from British Police.

However, West Yorkshire police have confirmed they are 'actively seeking' Hewlett in connection with an indecent assault on an eight-year-old in 1975.

Yesterday sick letters he wrote to his own daughter were revealed. Gina, 41, was 20 when he scrawled the self-pitying missives from his cell at Risley remand centre in Warrington, Cheshire, in March 1988.

In the letters he told her she was his 'favourite girl, the only trouble is you grew up'.

Hewlett's son Wayne, 40, a builder, said he was savagely beaten by him as a child. Wayne cut all ties with his father 20 years ago, and said: 'He is a monster.'