British police officers investigating the disappearance of Madeleine McCann have found no evidence relating to her after completing their search of three sites close to where she went missing.
However, Scotland Yard said "more activity has been agreed" and confirmed on Wednesday evening that more will be carried out “shortly”. Further requests are also being compiled and will be submitted to the Portuguese authorities.
Officers have spent over a week investigating areas of interest in the Algarve resort of Praia da Luz and are now due to question “several suspects” of interest to the case, according to unconfirmed reports by the BBC.
After police declined to comment about the recent activity in the resort, a statement from Scotland Yard said there was "still a substantial amount of work yet to be completed in the coming weeks and months".
The Madeleine McCann case
The Madeleine McCann case
1/25 Madeleine McCann
One of the last photos of Madeleine before her disappearance
2/25 Madeleine McCann
Madeleine McCann was three when she was abducted during a family holiday in 2007
3/25 Top worn by a man that detectives investigate with connection to disappearance of Madeleine McCann
A computer generated image of the distinctive burgundy long sleeve top worn by a man that detectives investigating the disappearance of Madeleine McCann are looking for
4/25 Apartment in Portugal from where Madeleine went missing
An aerial view of the Ocean Club apartments and pool where Madeleine McCann went missing
Jeff J Mitchell/Getty Images
5/25 Kate McCann
Kate McCann speaks to the press outside the court house in Lisbon on 12 September 2013 following the first audience of the McCann couple's libel proceedings against former inspector Goncalo Amaral for a book written about the case of their missing daughter
6/25 Kate and Gerry McCann
Kate McCann and Gerry McCann before the start of the 'Miles for Missing People' charity run in Regent's Park in London, 2011
7/25 Kate and Gerry McCann
Kate and Gerry McCann make an appeal at a press conference in the holiday resort of Praia da Luz, Portugal 7 May 2007
8/25 Kate and Gerry McCann
The McCann's give an interview with a Spanish television channel at their home in Rothley
9/25 Kate and Gerry McCann
Madeleine McCann was abducted in Portugal in May 2007
10/25 Kate and Gerry McCann
Preliminary forensic analysis on samples recovered from the McCanns' hire car raised the possibility of a match with Madeleine's DNA profile, according to the leaked report
11/25 Kate and Gerry McCann
Pope Benedict XVI blesses a photo of four-year-old abducted British girl Madeleine McCann, while meeting her parents Gerry and Kate McCann, after his weekly general audience at the Vatican, 2007
12/25 Kate and Gerry McCann
Gerald McCann and Kate McCann speak to the press on 4 May 2007 at the Ocean club appartement hotel in Praia de Luz in Lagos after Madeline vanished while her parents were out to dinner
13/25 Portuguese police search for Madeleine
Dozens of Portuguese police aided by dogs search for missing three-year old British girl Madelaine McCann in front of the Ocean club appartment hotel in Praia de Luz in Lagos
14/25 Kate and Gerry McCann
Gerald McCann and Kate McCann walk holding their two other children outside the Ocean club apartment hotel in Praia de Luz in May 2007
15/25 Madeleine McCann
Madeleine McCann pictured at the age of three, left, and as she might have looked aged nine
16/25 Kate and Gerry McCann
The parents of missing Madeleine McCann have described as "pure speculation" reports in the Portuguese press suggesting that a chief suspect in the disappearance of their daughter was killed in a tractor accident four years ago.
17/25 Tribute for missing Madeleine in Rothley, Leicesteshire
Three year old Cally prepares to add a yellow ribbon to a floral tribute for missing Madeleine McCann in Rothley in Leicesteshire, 2007
18/25 Support for the missing Madeleine
Everton captain Lee Carsley (L) leads his team onto the field, followed Mikel Arteta (C) and Manuel Fernandes (R) wearing Tshirts bearing a message of support for the missing British toddler Madeleine McCann, prior to the English Premiership match between Chelsea and Everton, at Stamford Bridge in London, 2007
19/25 Madeleine McCann
A poster appealing for information about Madeleine McCann at a Spanish railway station
20/25 BBC's Crimewatch reconstruction of Madeleine McCann's disappearance
Former porn star Mark Sloan (L) was cast in the BBC's Crimewatch reconstruction of Madeleine McCann's disappearance
21/25 Clarence Mitchell holds two artist's impression of the new suspect
McCann family spokesman Clarence Mitchell holds two artist's impression of the new suspect on 20 January 2008 in London. The description has come from British woman Gail Cooper, who was staying with her family close to the McCann's apartment in Portugal
22/25 Image of a woman sought in the case
Clarence Mitchell, the press spokesman for the McCann family, releases a photofit image of a woman sought in the search for missing Madeleine McCann
23/25 Suspect in disappearance of Madeleine McCann
Police released two e-fits of suspect in disappearance of Madeleine McCann
24/25 Raymond Hewlett
Convicted paedophile Raymond Hewlett, who is being sought in connection with the disappearance of Madeleine McCann
25/25 A picture of a suspect
An artist's impression of a suspicious man seen by a witness apparently watching the McCann family's apartment in Praia da Luz, Portugal, the day before Madeleine McCann went missing
This recent work is part of ensuring that all lines of inquiry are progressed in a systematic manner and covers just the one hypothesis that she was killed and buried locally," the statement said.
"This is the same as would be done in the UK for a murder or high risk missing person inquiry."
It described the deployment to Portugal over the past few weeks as the "largest ever undertaken by UK police overseas in a case of this type", with a total of 645,000 square feet of land searched, including all utilities, drainage channels and derelict buildings.
Police said the decision to search the scrubland which lies close to the Ocean Club resort where Madeleine went missing from an apartment aged three in May 2007, along with the two other sites investigated today, was a specific result of the UK's investigation work to date.
British officers, accompanied by their Portuguese counterparts, spent seven days carrying out a methodical search of the first site last week.
Specialist teams including forensics officers, sniffer dogs and officers using ground-penetrating radar equipment were used on the large site, with the two areas searched today being smaller and on the outskirts of the town.
The Portuguese have also reopened their inquiry into Madeleine's disappearance but, while they are working with the UK force, have refused to establish an official joint investigation.
The searches have seen Operation Grange police officers working alongside specialists from around the UK including Sussex Police and South Wales Police, along with the Portuguese Policia Judicial and Guarda Nacional Republicana.
Additional reporting by Press Association