The private detectives seeking Madeleine McCann say they are hunting a Briton who fled Praia da Luz after being accused of grooming an under-age girl for sex.

Part-time barman and disc jockey Christian Ridout, 32, allegedly sent the British girl obscene text messages when he worked in an expats' pub 200 yards from where Madeleine disappeared.

When the 12-year-old's mother discovered the explicit messages, Ridout - also known as DJ Shifty - left Portugal in a hurry.

This was some time before Madeleine disappeared on May 3 - but the missing man's parents still run the same pub and concerned locals immediately gave his name to police.

Portuguese officers, widely criticised for a series of blunders in the Madeleine case, have never succeeded in tracing Ridout.

The spokesman for Madeleine's parents Gerry and Kate confirmed that the Spanish detective agency working for them, Metodo 3, was seeking more information on the missing man.

The mother of the 12-year-old told the Daily Mail: "He was sending my daughter messages offering to pick her up from school, and suggesting the most disgusting sex acts. It went on for two months before I found out."

By coincidence, the Ridout family were next-door neighbours of the family of Robert Murat, the chief suspect in the Madeleine hunt, when the Murats lived in the nearby village of Almadena.

The night after Madeleine went missing, a British expat walked into the Plough and Harrow pub in Praia da Luz, still owned by his parents Tony, 57, and Jill, 58, and asked: "Where's Christian then'".

Locals have disparagingly nicknamed the pub 'The Plough and Paedophile' and the missing man is widely disliked in the tight-knit community.

The Daily Mail has been shown an image of Mr Ridout acting indecently while wearing a Santa hat, which was taken at a Christmas party several years ago and which he stored on his computer.

And numerous people in Praia da Luz have reported that he regularly talked about his interest in 'pre-teen' girls.

The mother of the 12-year-old, who lives near Praia da Luz in Burgau, said: "I came to the Algarve five-and-a-half years ago and started working in the Plough and Harrow.

"I did the day shift in the bar, while Christian Ridout took over for the night shift. He was always coming out with rude innuendos, and he'd tell people who didn't know him that he was 21, even though he was 30.

"My two daughters, then 12 and 14 used to come in to see me, and Christian used to talk to them, and eventually it turned out he'd got my youngest girl's mobile number."

Some weeks later, in 2005, the 42-year-old woman heard a rumour that Mr Ridout had been sending the girl disgusting texts.

"I asked her if she'd been getting any messages from Christian - and she had, about 25 of them. They got progressively more obscene. They were talking about her being a virgin, telling her he'd done 'it' before and that he'd be gentle and it wouldn't hurt.

"He was suggesting he should pick her up from school. The messages were absolutely vile.

"My youngest girl is quiet - and police said that it was a clear case of grooming. It was very sick. I couldn't even read the final ones, but just phoned Christian. I said, 'If you come anywhere near my daughters again I'll kill you.'

"He took all the money from the till at the Plough and Harrow and went to Spain that night.

"They later found his VW Golf at Seville airport, with his keys left hidden in the wheel arch and he was believed to have gone back to England.

"The next day I went to see the Ridouts and resigned.

"I went to the police station in the large regional town of Portimao, and they took all the explicit messages. I went in to see them just before Madeleine disappeared and they confirmed they're still looking for him. 'No one knows where he is, but he could have been back to this area."

Jill Ridout said: "I haven't seen Christian for two years. I have no comment on this subject."