A NEW investigation into the disappearance of Madeleine McCann was under way last night after senior Scotland Yard detectives flew to Portugal.

Officers from a 30-strong squad specially set up to revive the search for Madeleine McCann, who vanished four years ago, met Portuguese authorities for the first time.

The top secret talks took place last month but details emerged for the first time yesterday.

Last night Madeleine?s devoted parents Kate and Gerry told how the development gave them fresh hope of a breakthrough in the hunt for their daughter. Heart specialist Gerry, 42, and former GP Kate, 43, were said to be ?extremely pleased? the meeting had taken place. 

It is the first time any international police force has been searching for Madeleine since the official Portuguese inquiry was shelved in July 2008. The couple?s spokesman Clarence Mitchell said Kate and Gerry believed it was ?a positive step in the right direction?.

Madeleine disappeared during a family holiday in the Algarve resort of Praia da Luz on May 3, 2007.

Scotland Yard confirmed its officers conducted their first face-to-face ?formal meeting? with Portuguese police who led the hunt for her.

The McCanns, of Rothley, Leicestershire, believe vital clues were missed and leads never followed up during the shambolic investigation.

The despairing couple were left to search for Madeleine by themselves and hired a team of private eyes.

They insisted they would never stop looking for Madeleine, who vanished days before her fourth birthday, and were given a huge boost when David Cameron stepped in to help following a personal appeal in May.

Mr Cameron told the couple Home Secretary Theresa May had ordered Scotland Yard to launch a new operation funded by the Government. They were tasked to carry out a review of the investigation from start to finish and bring a new perspective to the case.

Yesterday it was revealed the Yard team carrying out the new inquiry consists of 30 officers, the same size as a murder squad.

It is being led by Detective Chief Inspector Andy Redwood, of the Met?s Homicide and Serious Crime Command, who has been dubbed Britain?s top cold case detective. The McCanns hope the renewed efforts could unearth a vital new clue in the four-year mystery.

Mr Mitchell said: ?Kate and Gerry are extremely pleased that the review is progressing. It is a positive step in the right direction.?

The Portuguese detectives? investigation, helped by officers from Leicestershire Police, led to hundreds of possible sightings of Madeleine across the world but so far all have come to nothing. A Scotland Yard spokesman said last night: ?Officers from the Metropolitan Police travelled to Portugal at the beginning of August and had their first formal meeting with Portuguese authorities to discuss ways to progress the investigative review.?

The McCanns met members of the London-based squad several times before the Portuguese meeting. A source close to the couple said: ?They are relieved. Things are finally being done and Kate and Gerry are being kept informed of every move.? The couple, who have six-year-old twins Sean and Amelie, are convinced it is only a matter of time before they get a significant breakthrough.

Their private investigators, headed by former Detective Inspector David Edgar, have also met the new team.

The family source said: ?Kate and Gerry have had several meetings with police reviewing their daughter?s case. They know the officers have a difficult task ahead but they feel positive. They have been told that if something has been missed they will find it. They are relieved that something is finally happening.

?Kate and Gerry believe potentially vital clues were missed in the botched Portuguese investigation and their private eyes are hoping the Met will bring a new perspective to the case, which is being conducted in tandem with Portuguese police. The review is still in its very early stages. Officers are busy going through everything from scratch and analysing it.?

When the review was announced, Sir Paul Stephenson, the then Metropolitan Police Commissioner, insisted there was ?always a chance? it could lead to Madeleine being safely reunited with her parents.

The review team has drawn expertise from Scotland Yard?s specialist crime directorate.

More officers will be drafted in if new evidence is found, including scenes-of-crime experts and forensic scientists.

The team is currently sifting through 20,000 pages of evidence assembled by Portuguese detectives. They will review witness statements, make a fresh appeal for ?information and carefully re-check alibis.

A police source said: ?They will be looking for something that has been overlooked or not developed which could lead to a fresh line of inquiry ? a sighting, a tip-off, something that didn?t ring bells at the time but could be vital.?