The cost of the continuing British police investigation into the disappearance of Madeleine McCann could soon hit £10 million.
The spend is part of a review into the case ordered by David Cameron in 2011, with an initial budget of £5 million.
Operation Grange has seen Metropolitan Police officers travel to Portugal to work with authorities in efforts to find new leads on the seven-year-old mystery.
The Home Office is proving funding to the Mayor’s Office for Policing and Crime for the operation, with the total standing at £7.9 million to date, according to figures released following a freedom of information request.
In 2011/12, £1.9 million was awarded, followed by £2.8 million in 2012/13, £2.6 million last year and £639,000 to date in 2014.
A spokesperson said the Home Office expected this year’s costs to be “broadly in line with previous years”, meaning it could bring the total to £10 million.
“The costs of the operation are regularly reviewed to ensure they are proportionate,” the spokesperson added.
Madeleine, from Rothley in Leicestershire, went missing on 3 May 2007, after she disappeared from her bed at the Ocean Club complex in Praia da Luz.
The three-year-old and her two younger siblings had been left asleep in a bedroom of the apartment while her parents dined with seven other friends at a Tapas restaurant 50 metres away.
She was discovered missing by her mother, Kate McCann, later that night but initial searches turned up no clues and a Portugese police chief, Olegario Sousa, later admitted that vital forensic clues may have been destroyed.
As part of Operation Grange, police have made renewed appeals on television in the UK, Ireland Netherlands and Germany with a photograph simulating how Madeline would look now, aged nine.
After shelving their inquiry into Madeleine's disappearance in 2008, Portuguese authorities said last October that a review had uncovered enough new information to justify reopening it.
In March, an intruder with a distinctive odour, who is suspected of breaking into holiday homes to sexually assault young girls, emerged as a new suspect in the Met Police’s investigation and in April, police confirmed they are investigating five new cases where young British girls were sexually assaulted during home-break-ins in the Algarve.
Since launching its own investigation, 41 people of interest have been identified by the Metropolitan Police.
Detectives have issued 31 international letters of request (ILOR) to mostly European countries in relation to some of the possible suspects well as accessing phone records.