PORTUGUESE police investigating the disappearance of Madeleine McCann are to question a former suspect.

A source close to the case has reportedly revealed to the BBC that Robert Murat, one of 11 people being interviewed by officers in Portugal, will be treated as a witness.

He has always denied any involvement in the disappearance and said that his conscience "is clear".

Madeleine was three when she went missing in Praia da Luz in May 2007. She was on holiday with her mother Kate and father Gerry, who is from Glasgow, when she disappeared from their apartment.

Mr Murat was the first person to be declared a suspect or 'arguido' in the investigation and was later cleared by police in Portugal. He won substantial damages from various media organisations and has always denied any involvement in Madeleine's disappearance.

Mr Murat told the BBC neither he nor his lawyer had received a formal request to appear, but said he "would do so freely". He said: "My conscience is clear and I have no problem speaking to the police again."

Mr Murat's wife has also been listed as one of the four witnesses the Metropolitan Police wish to have questioned regarding Madeleine's disappearance.

Four of the 11 speaking to police are being interviewed as witnesses and seven as 'arguidos' - a status in the Portuguese judicial system referring to individuals whom police may reasonably suspect are linked to a crime.

British detectives had been scheduled to fly out to observe the questioning next week, but this was postponed on Tuesday night as a result of what are believed to be legal technicalities.

British police can sit in on the interviews but are not allowed to ask direct questions.

Mr Murat, an expat who lives in Portugal, was first questioned as an 'arguido' in 2007 but that status was later removed. The following year he was awarded £600,000 in libel damages from 11 newspapers.

In June, Portuguese and British police searched three sites in the Algarve resort but found no evidence.