Police sealed off the villa, known as Casa Liliana

He is believed to be Robert Murat, who shares a villa with his mother Jenny in Praia da Luz, Algarve.

The man, who has since been released by police, may have requested suspect status for the legal rights it gives.

Officers searched the villa 150 yards from where four-year-old Madeleine of Rothley, Leicestershire, was last seen, and questioned three people.

Under the Portuguese legal system, arrests can only be made when police designate someone as an "arguido" or suspect, although no-one has been arrested yet in this case.

ARGUIDO STATUS Officially a suspect Bestowed by police or requested by individual Right to remain silent Right to a lawyer Must report to police every five days

A person may also ask for the arguido process to be invoked as it gives them specific protection such as access to a lawyer and the right to remain silent.

BBC correspondent Richard Bilton said a British man in his 30s has been given arguido status.

It is understood the other people questioned were a German woman and a Portuguese man.

The search of the property known as Casa Liliana began at 0700 local time on Monday after Sunday Mirror journalist Lori Campbell had spoken to the British Embassy and the police about Mr Murat.

He had become well known to journalists during the search for Madeleine.

Mr Murat, formerly of Hockering, Norfolk, describes himself as half-Portuguese and told reporters he had been helping police with translation work during the investigation.

Mr Murat's mother is a 71-year-old former nurse who has lived in Portugal for 40 years and brought her son and daughter up in the country.

His mother says that on the night the kid disappeared they were both in the house together all night Ralph Eveleigh, Robert Murat's uncle Prayers for Madeleine

Catherine Roberts, a friend of the family in Portugal, said: "Jenny is very well known around here - she has lived here most of her life.

"And the family has a very good reputation and a very good name."

Mr Murat's uncle, Ralph Eveleigh, who runs a bed and breakfast in the nearby village of Burgau, said his nephew had an alibi for the night Madeleine went missing.

"His mother says that on the night the kid disappeared they were both in the house together all night," he said.

"Robert is so sweet and good-natured. He was just trying to help."

The villa is owned by Jenny Murat and used by her son Robert

Mr Murat's cousin, Sally Eveleigh, said there was "absolutely no way" he could have had anything to do with Madeleine's disappearance.

Officers in white suits with facemasks were seen at the Murat's villa and in its grounds on Monday evening.

It is believed police have drained its swimming pool and taken away computers, mobile phones and several video tapes.

Madeleine is believed to have been abducted while her parents were eating at a tapas bar.

On Monday, her parents Kate and Gerry McCann said they would not return to the UK until she was found safe and well.

Mr McCann, who is originally from Glasgow, said the couple would continue to believe she was being cared for until they received "concrete evidence to the contrary".

The international number for Crimestoppers is +44 1883 731 336. People with information about Madeleine can call anonymously.