Police investigating the 2007 disappearance of Madeleine McCann have started searching a reservoir in Portugal.
Up to 30 officers could be seen on Tuesday at the Arade dam, about 50km from Praia da Luz, where Madeleine, who was three at the time, was last seen alive.
Police were seen searching the bank beside the dam with the help of a sniffer dog, while officers searched the water on board a fire department boat.
German prosecutors confirmed the search was taking place but said they could not give further details "for tactical, investigative reasons".
A blue tent was cordoned off to the press and the public.
The search was requested by German police and was being carried out with the help of British officials in connection with a formal suspect in the case.
German police are assisting the Portuguese authorities, the German prosecutors said, while London's Metropolitan Police said it also had officers on the ground.
German citizen and convicted sex offender Christian Brueckner, 45, was in the Algarve in 2007. He has denied any involvement.
German prosecutors in Braunschweig on Tuesday said “criminal procedural measures are currently taking place in Portugal as part of the investigation into the Madeleine McCann case”.
They added “the measures are being implemented by way of mutual legal assistance by the Portuguese prosecution authorities with the support of officers from the Federal Criminal Police Office”.
“More detailed information on the background is not being released at this time for investigative tactical reasons,” a statement said.
Brueckner is serving a seven-year prison sentence in Germany for a rape he committed in Portugal in 2005.
He is under investigation on suspicion of murder in the McCann case but has not been charged. He spent many years in Portugal, including in Praia da Luz, around the time of Madeleine’s disappearance. His yellow-and-white camper van was reportedly spotted near the area where she went missing and he is said to have called the reservoir “his little paradise”.
The Madeleine McCann case – in pictures
Her disappearance stirred worldwide interest for several years, with reports of sightings of the missing girl as far away as Australia, along with a number of books and TV documentaries about the case.
Rewards for finding Madeleine, who would now be 20, reached several million dollars.
British, Portuguese and German police are still piecing together what happened on the night she disappeared from her bed in the southern Portuguese resort on May 3, 2007.
She was in the same room as brother and sister, twins who were two at the time, while her parents had dinner with friends at a nearby restaurant.