Investigations have so far failed to find Madeleine McCann

Madeleine McCann's father Gerry McCann has returned to Portugal to advise private detectives filming a reconstruction of her disappearance.

Family spokesman Clarence Mitchell said Mr McCann and two family friends have returned to the resort area of Praia da Luz to help with the filming.

The reconstruction will be shown in a Channel 4 Cutting Edge documentary.

Madeleine, of Rothley, Leicestershire, was three when she vanished from the Algarve holiday flat on 3 May 2007.

The aim of this is to get that critical piece of information that could still help to find Madeleine

Family spokesman Clarence Mitchell

The reconstruction - being filmed by the McCanns' own private investigators - will focus on what happened on the night, as described by witness statements.

Negotiations are under way for the reconstruction to be shown on Portuguese television and in other European countries, and it will be also be available on the Find Madeleine website.

Mr Mitchell said: "The aim of this is to get that critical piece of information that could still help to find Madeleine. Gerry has returned with that aim.

"Certain aspects of the witness testimony were hidden deep in the police files and these particular aspects have received very little attention. The private investigators feel that it is very important to highlight these things.

"It's being done simply in the hope that it will jog someone's memory."

'Harrowing'

The McCann's friends Jane Tanner and Matthew Oldfield, who were with them on the night Madeleine disappeared, will be interviewed on the programme, to be aired on 7 May.

A man was said to have been "acting suspiciously" two days before Madeleine disappeared, and Ms Tanner said she had seen a man carrying what may have been a sleeping child.

Channel Four commissioning editor for documentaries Mark Raphael said: "The disappearance of Madeleine McCann is one of the most harrowing unsolved crimes of recent years.

"Two years on, Kate and Gerry McCann are still searching for their daughter. We hope that this documentary and reconstruction may be able to provide vital new leads for the investigation."