Six key witnesses have now cast serious doubt on the alibi of Madeleine McCann suspect Robert Murat.

The latest is a British barrister who insists he saw Mr Murat in the hours after the three-year-old vanished from her holiday apartment in Portugal - at a time when the suspect claimed he was with his mother.

Madeleine's mother Kate has now told friends she has her own suspicions over Mr Murat, and has demanded he tells the truth over his whereabouts on the night the girl disappeared.

Six key witnesses have cast doubt over Robert Murat's alibi

The key witnesses are:

' Holidaymaker Jayne Jensen, a 54-year-old businesswoman. In a statement to police she said she saw Mr Murat smoking a cigarette on the street corner opposite the apartment half an hour after Madeleine disappeared.

'The barrister, who has not been named but was on holiday and was pictured in Praia da Luz at the time Madeleine vanished. He has given a witness statement that corroborates what Ms Jensen said.

The next evening he and Ms Jensen were talking about the disappearance on an apartment balcony when Mr Murat joined them for a drink.

The barrister has described Mr Murat's behaviour that evening as "odd", saying Mr Murat insisted on going to change his clothes because it had been a long day - when they were certain he had already changed earlier.

Conflict: Madeleine's mother Kate McCann believes Robert Murat is not telling the truth about the night her daughter disappeared

' Three friends of the McCanns. It is understood they have given statements to police insisting Mr Murat introduced himself to them on the night Madeleine vanished. It is claimed he said: "I am Robert. Can I help in the search'" Mr Murat subsequently acted as a translator between the police and the McCanns up until he was made a suspect.

' Charlotte Pennington, a nanny working at the Ocean Club resort. She claims to have seen Mr Murat in the hours after Madeleine vanished.

A source close to Mrs McCann told the Standard: "Kate has always felt there are questions concerning Murat that need to be answered.

"Gerry doesn't know whether he is involved but Kate has always been suspicious. There is a body of evidence contrary to what he [Murat] is saying.

"He has said he was not there on the night and now we have a number of people who have come forward quite independently of us and have volunteered information directly in contradiction to what he has said.

"The latest witness is a barrister who has corroborated what others have said."

Mr Murat, 34, strongly denies any involvement in Madeleine's disappearance on 3 May. He has always claimed to have spent the evening at his mother Jenny's villa a hundred yards from where the girl vanished.

Key witnesses: Sisters Jayne Jensen, left, and Annie Wiltshire were in Praia da Luz

Earlier this month Mrs Murat, 71, said anybody who claimed to have seen her son on the night of 3 May was a liar. But she also appeared to contradict her son's version of how he learned Madeleine was missing.

Mrs Murat claimed she woke him up in the morning to tell him the news of the missing child. But, according to the official version, his lawyer Francisco Pagarete said Mr Murat was in his garden when he found out from a British holidaymaker helping in the search.

Investigators are probing Mrs Murat's claim. A source close to the McCanns said: "Murat was there that night. His mother may be protecting him.

"He is her son and most mothers would protect their children. Either she knows something or she is mistaken."

Murat helps police as the investigate Madeleine's disappearance

Doubts over Mr Murat's alibi do not prove he has any connection with Madeleine's disappearance, and police are understood to have found no forensic links.

But he has been an official suspect for more than seven months despite repeated claims in Portuguese media that he would be cleared at any moment.

It is understood his lawyer could seek to have his suspect status removed on Thursday, but this bid is likely to fail while the investigation continues.

The McCanns, from Rothley in Leicestershire, also remain suspects, although the police investigation appears to be moving away from their involvement.