Detectives from Scotland Yard involved in investigating the disappearance of Madeleine McCann are understood to have arrived in Portugal to help with the excavation of a number of sites in the Praia da Luz resort where the three-year-old went missing seven years ago.
Madeleine vanished on 3 May 2007, after she disappeared from her bed in the Ocean Club resort.
Portuguese authorities reportedly approved plans by the Met Police to dig for evidence near the Ocean Club earlier this week.
On Tuesday, Met Police Assistant Commissioner Mark Rowley said he believed “activity” would occur within the next few weeks, but would not be able to provide any further details on what this would entail.
A letter was subsequently sent to media outlets, where Mr Rowley asked them to "think carefully" about the information they publish.
He said Portuguese police did not give media updates on ongoing investigations, and this “activity” would cease if British police provided any information on the continuing investigation to journalists.
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
Forensic teams will use ground penetrating radar equipment to examine three sites in Praia da Luz, in an operation that comes just days after the seventh anniversary of Madeleine’s disappearance.
Read more: Madeleine McCann: The case so far
The excavations, which are expected to be conducted by forensic experts, are not thought to necessarily be in connection with a search for the youngster's body or remains.
A road close to the Ocean Club resort, wasteland next to the complex where witnesses reported seeing a man walk past carrying a girl towards the sea, and a beach just a short walk away, are the three sites officers are expected to search.
Madeleine’s mother Kate McCann has previously expressed frustration at the pace of the Portuguese investigation, describing it as “really hard to take” and “distressing”.
"To us, it makes sense that the two police forces should work together, to have a more streamlined approach to avoid duplication and basically to progress the investigation at a faster pace,” she told the BBC earlier this month.