Madeleine McCann's family will issue a new plea for information in their search for the missing little girl today.

The appeal will be made by one of the retired British policemen hired by the child's parents to investigate her disappearance in Portugal more than two years ago.

Former detective inspector Dave Edgar will appear alongside McCann family spokesman Clarence Mitchell at a press conference in central London this morning.

Details of the appeal have not been released yet, but it is understood that it stems from a new witness who has come forward to the McCanns' private investigators, and includes connections to Australia and Spain.

Madeleine's parents, Kate and Gerry McCann, from Rothley, Leicestershire, will not attend the news conference, Mr Mitchell said.

Mr Edgar and a second retired British detective, Arthur Cowley, were hired by the McCanns to continue the search for their daughter after the official Portuguese investigation was shelved in July last year.

The two former policemen have visited a number of European countries in the pursuit of leads, including the possibility that a convicted British paedophile might know something about the child's disappearance.

Raymond Hewlett, who was jailed several times in the UK for sexually assaulting young girls, is said to have been staying an hour's drive from the McCanns' Portuguese holiday flat when Madeleine vanished.

He is being treated for cancer in Germany and denies all involvement in Madeleine's disappearance.

Mr Mitchell said the investigators had not yet managed to talk to Hewlett but he remained a "person of interest".

Madeleine was nearly four when she went missing from Praia da Luz in the Algarve on May 3, 2007, while her parents dined with friends nearby.

Despite a massive investigation by Portuguese and British police and huge publicity worldwide, she has not been found.

It emerged this week that Leicestershire Police have spent nearly £750,000 investigating her disappearance.