Media playback is unsupported on your device Media caption A 25-minute reconstruction has been staged for Crimewatch

The timeline and "accepted version of events" surrounding Madeleine McCann's disappearance have significantly changed, British police say.

The Metropolitan Police said a BBC Crimewatch appeal to be aired on Monday would feature "the most detailed reconstruction" of the case yet.

It will also broadcast e-fits of a number of men police want to find.

Madeleine, of Rothley, Leicestershire, was three when she went missing in Portugal in May 2007.

Portuguese authorities dropped their investigation into the case in 2008, but Scotland Yard started a review in May 2011.

It has yet to give any details, ahead of the Crimewatch appeal, about how its understanding of events in May 2007 has changed.

Madeleine disappeared from her family's holiday flat in the Algarve resort of Praia da Luz, as her parents, Kate and Gerry McCann, dined out with friends at a nearby restaurant.

'New significance'

The purpose of the Crimewatch appeal, which police are describing as the "most complex and detailed" so far in the case, is to try to identify a number of computer-generated images, or e-fits, of men who were sighted in and around Praia da Luz on or before Thursday 3 May 2007.

As part of that effort, a reconstruction - almost 25 minutes long - of events leading up to and surrounding Madeleine's disappearance will be shown.

Image caption The McCanns released this picture of Madeleine during the search for her

A short clip released in advance by police shows an actress playing Madeleine running across a tennis court as two adults, apparently her parents, play a game.

During the search for their daughter, the McCann family released a photograph of Madeleine, believed to be one of the last taken of her during the holiday, holding several tennis balls.

Media playback is unsupported on your device Media caption Gerry McCann: "When it's a special occasion... and Madeleine's not there - that's when it really hits home"

Det Ch Insp Andy Redwood, who is heading the investigation, said: "The timeline we have now established has given new significance to sightings and movements of people in and around Praia da Luz at the time of Madeleine's disappearance.

"Our work to date has significantly changed the timeline and the accepted version of events that has been in the public domain to date.

"It has allowed us to work with Crimewatch to build the most detailed reconstruction as yet, and highlight very specific appeal points.

"I hope that when the public see our investigative strands drawn together within the overall context of that appeal, it will bring in new information that moves our investigation forward."

DCI Redwood said that police had sought to "try and draw everything back to zero... take everything back to the beginning and then reanalyse and reassess everything, accepting nothing".

Phone records

He added: "The careful and critical analysis of the timeline has been absolutely key. Primarily, we are focused on the area between 8.30pm and 10pm.

"We know that at 8.30, that was the time that Mr and Mrs McCann went down to the tapas area for their dinner, and we know that at around 10pm, that was when Mrs McCann found that Madeleine was missing."

Image caption An image (R) of how Madeleine might have looked aged nine

Madeleine's parents will make a live appeal in the studio during the programme and, ahead of the broadcast, they told the BBC how much they still miss her.

"When it's a special occasion, when you should be at your happiest, and Madeleine's not there, that's when it really hits home," Mr McCann said.

Mrs McCann added: "It's when you have the big family occasions... and you haven't got your complete family."

Earlier this month, police said phone records may be key to the case after it emerged officers were analysing data from phones belonging to people who were in Praia da Luz when Madeleine vanished.

The Crimewatch appeal, which will be shown in the UK on BBC One on Monday from 2100 BST, will also be broadcast in the Netherlands and Germany.