The parents of missing girl Madeleine McCann have pleaded with a convicted paedophile to "see sense" and cooperate with private investigators dealing with the case.
The McCanns' investigation team wants to interview 64-year-old Raymond Hewlett in the next few days in the hope he can shed some light on their daughter's disappearance from a holiday flat in Praia da Luz, Portugal, in May 2007.
Hewlett is alleged to have been staying near the McCanns' resort flat when she went missing.
UK-born Hewlett, who previously lived in Blackpool and Telford, is reportedly being treated for throat cancer in hospital in the German city of Aachen. He was jailed several times for sexually assaulting young girls and is now wanted for questioning by British detectives in connection with a separate indecent assault.
The McCanns hope that once officers from West Yorkshire Police have questioned the former soldier, their investigators will speak to him, despite reports he is seriously ill in intensive care.
Clarence Mitchell, Kate and Gerry McCann's spokesman, said: "Mr Hewlett has denied any involvement in Madeleine's abduction.
"Our investigators hope he will see sense and co-operate by giving them whatever information needed so they can eliminate him from the investigation.
"It's clear the man is ill and it is clear he has information that our investigators need. It is also clear that our investigators will be speaking to him in the near future."
It is understood that before the McCanns' team can speak to Hewlett, British officers will interview him in connection with an indecent assault in 1975.
Sources close to the investigation say they think both interviews will take place in "a matter of days, not weeks".
The McCanns currently have two retired detectives who they hired to search for their daughter. They hope British police will help facilitate an interview with Hewlett.
But a source with knowledge of the investigation admitted Hewlett was a "private individual" who could "in theory say no" to an interview with the McCanns' detectives.
Yesterday, a spokeswoman for West Yorkshire Police said the force could not go in to details about why British officers wanted to speak to the convicted paedophile.
The spokeswoman added: "We have made contact with the German authorities. We are just waiting for clearance so we can actually go and speak to him regarding that incident."
Questions have been raised about Hewlett's time in Portugal by a couple who met him on holiday.
Alan and Cindy Thompson said the sex offender was living with his wife and six children in a converted Dodge truck travelling from campsite to campsite in the Algarve and southern Spain.
Hewlett allegedly told the Thompsons he was approached by some "Gipsy tourists" offering to buy his daughter just before Madeleine went missing.
They also recalled him mentioning a "business" trip to Morocco, where there were several alleged sightings of the little girl in the months after her disappearance.
Hewlett told the Thompsons he was at a market in the Portuguese town of Fuseta, 30 miles from Praia da Luz, when Madeleine vanished, according to the Mirror.
He reportedly told the couple he had done nothing wrong and they were judging him based on what they knew of his past.
He said: "If you've chosen to believe anything I can't do anything about it anyway, so there you go. Catch 22.
"You're basing it on someone's past, rather. That means the person's past is important. Doesn't make him guilty. You shouldn't be talking to me about it. I've done nothing wrong, nothing, nothing."
It is believed the Thompsons attempted to contact British police with their concerns about Hewlett some time ago but were not successful.
Leicestershire Police, which handled the British end of the inquiry into what happened to Madeleine, refused to comment.
A spokeswoman for the force said: "The disappearance of Madeleine McCann remains a Portuguese investigation. We would pass any relevant information we receive to the Portuguese police."
The McCanns' private investigators yesterday flew back to the UK from Portugal, where they have been chasing up information received from the public since a blaze of publicity around the second anniversary of Madeleine's disappearance.
It is understood the leads include the names of a number of suspects.
Madeleine was nearly four when she went missing from her family's holiday apartment in Praia da Luz on May 3, 2007 while her parents dined with friends nearby.
Despite a massive police investigation and huge publicity worldwide she has not been found.