Final attempts by private detectives searching for Madeleine McCann to interview a convicted British paedophile about her disappearance have failed.

Retired police officers Dave Edgar, who served in Northern Ireland, and Arthur Cowley flew to Germany on Tuesday hoping to speak to Raymond Hewlett, who is said to have been staying an hour’s drive from the McCann’s Portuguese holiday flat when the little girl vanished.

But negotiations between the private investigators and Hewlett’s German lawyer broke down yesterday.

Mr Edgar, who has been employed by Madeleine’s parents Kate and Gerry McCann to look for their daughter, said he was “very disappointed” with the lawyer’s behaviour.

He went on: “I have been attempting to speak with Raymond Hewlett to eliminate him from our investigation into the disappearance of Madeleine McCann.

“He is not a suspect but I was keen to interview him because of his failing health. I have tried over the past weeks to arrange this via his lawyer in Germany.

“These negotiations have been difficult for reasons which I do not want to go into detail about.

“Mr Hewlett’s condition has of course been deteriorating during these negotiations.

“I travelled to Germany yesterday in a final effort to interview Raymond Hewlett. Regrettably that interview is not possible.

“From information provided by his lawyer and other sources, it is obvious that his health is such that any meaningful interview would not be possible.”

Mr Edgar, a former detective inspector who worked for the RUC and Cheshire Police, said Hewlett’s ability to answer questions accurately “must also be in doubt”.

The detective said he had been told that the paedophile could only manage a 60-minute interview when to quiz him properly about Madeleine’s disappearance would take five hours.

Mr Edgar added: “I will of course reconsider my position should Raymond Hewlett’s condition allow a proper, meaningful interview to take place.”

It is understood that the McCann’s detectives remained in Aachen in Germany overnight before returning to the UK.

Hewlett (64), is being treated for throat cancer in Aachen.