German police looking for Madeleine McCann’s body are set to begin a major search of a remote Algarve reservoir that suspect Cristian Brueckner previously visited.
Officials are soon expected to start closing off roads leading to the Barragem do Arade reservoir near the town of Silves, ahead of the official start of the search on Tuesday.
Scotland Yard detectives are understood to have travelled to the area, but will only have a “watching brief”.
The search is due to last for at least two days, and will continue beyond that if anything of relevance is found.
It will be the first major operation of its kind since June 2014, when British police were given permission to undertake digs in Praia da Luz involving sniffer dogs trained in detecting bodies, and ground-penetrating radar.
This time, expert divers are poised to explore the depths of the reservoir, and digs will take place in woodland next to the water.
A lorry driver previously claimed he saw a woman handing over a child who looked similar to Madeleine to a man at the reservoir, two days after the three-year-old went missing from her Praia da Luz holiday apartment on May 3, 2007.
The reservoir was searched twice before in February and March 2008 by divers hired by a Portuguese lawyer.
Marcos Aragao Correia organised the privately-funded operation after claiming he had been tipped off by contacts that Madeleine had been murdered and her body thrown into the reservoir within 48 hours of her disappearance.
Two bags containing small bones were found during the second search, after divers had earlier recovered several lengths of cord, some plastic tape and a single white cotton sock.
Portuguese police were alerted following the discovery, but subsequently ruled out the possibility the bones were human because of their size.
Gerry and Kate McCann, Madeleine’s parents, had previously dismissed Mr Correia as a self-publicist and said there was no evidence suggesting any link between their daughter and the reservoir.
It is not thought to have been searched since March 2008 as part of the investigation into her disappearance.