British police have met Portuguese detectives to plan new interviews with the group of friends who dined with Gerry and Kate McCann on the night their daughter Madeleine disappeared.

Portuguese police continue to believe the so-called Tapas Nine - the McCanns and their seven friends - could still hold the solution to the unsolved mystery that began in May last year.

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And Leicestershire Police said yesterday that Detective Superintendent Stuart Prior had returned from the Algarve after three days of meetings with counterparts in Portugal about how fresh interviews would be conducted.

Madeleine was three when she went missing from her family's holiday apartment in Praia da Luz while her parents ate dinner at a tapas bar 50 yards away with their friends from England.

Portuguese detectives, who have been widely criticised for their failure to find any solid evidence or charge anyone, remain unsatisfied by the witness accounts given by the so-called Tapas Nine, as they try to establish a timeline of events on that evening.

Leicestershire Police said Det Supt Prior flew to Portugal to discuss the issue of mutual legal assistance, the process whereby evidence is gathered in one country to help an investigation in another.

A Leicestershire police spokeswoman said: "Since Madeleine's disappearance, we, together with other law enforcement agencies, have been working closely with the Portuguese authorities.

"Mr Prior has attended a series of meetings with his Portuguese counterparts. He travelled to Portugal on Tuesday and returned this morning.

"He went to discuss how the request for mutual legal assistance is to be executed, and to seek clarification over elements of the request."

The process could involve Portuguese police writing questions to be put to the friends on their behalf by their British counterparts.

But officers involved in the investigation in the Algarve also fly to Britain to sit in on the interviews, which are likely to be held at a location in Leicestershire.

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The McCanns' spokesman Clarence Mitchell said: 'The sooner this re-interviewing takes place the better.

"The friends are very keen to help police understand their original statements. No one will be changing their story.

"We are not aware that Kate and Gerry are to be re-interviewed at this stage, but if so, that's not an issue."

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The McCanns, from Rothley in Leicestershire, were joined at the tapas restaurant on by Dr Matthew Oldfield and his recruitment consultant wife Rachael, Dr Russell O'Brien and his partner Jane Tanner, and medical researcher David Payne, his wife Fiona, and her mother Dianne Webster.

A Home Office spokeswoman said: "We have already confirmed that we have received a mutual legal assistance request from the Portuguese authorities in connection with the investigation into the disappearance of Madeleine McCann.

"We are currently awaiting clarification from the Portuguese authorities over elements of the request.

"Home Office officials continue to work closely with the police to assist the Portuguese authorities with this investigation."

British expat Robert Murat, 34, a sometime estate agent, was made an official suspect two weeks into the inquiry when police suddenly swooped on the villa he shares with his mother less than 100 yards from the McCanns' holiday flat.

He has not been charged, but remains under official suspicion.

Portuguese Police later made Gerry and Kate McCann themselves their chief targets, but again no charges have followed.