“Material collected” during three days of searching for Madeleine McCann will be sent for testing in Germany, say Portuguese police.
It comes as the operation ended with tents being taken down and heavy machinery removed.
Officers had been searching the reservoir and surrounding scrubland after receiving “certain tip-offs”.
It’s not yet known if anything significant was found but a number of bags were taken away.
Police said the search “resulted in the collection of some material that will be subject to the competent expertise”, and that it would “be handed over to the German authorities”.
Holes – believed to have been dug for soil samples – were found in the search area when it reopened.
A police boat entered the water at the Arade dam on the first day of the search on Tuesday and teams began to dig on a peninsula on Wednesday afternoon.
Eyewitness: Behind the police cordon of the Madeleine McCann search
Cut down trees and cleared land; that is what it looks like behind the police cordon of the latest search for Madeleine McCann.
After three days, officers finished their operation at Arade reservoir on Thursday afternoon.
Once the site was secured and restrictions were lifted, the authorities allowed journalists access.
The first things we saw were fire pits and then the piles of branches which had been chopped down by specialist machinery.
In some areas, the top layer of earth had been removed and holes had been dug in the mud.
The area is believed to be a favourite haunt of the prime suspect in the three year old’s disappearance.
Christian B, a known sex offender lived in the area when she went missing from an apartment in Praia da Luz in 2007.
He’s always denied any involvement but following a tip off, German authorities asked Portuguese police to assist in a new search.
Dozens of officers including representatives from Germany and the UK were involved in the operation.
At times police could be seen digging, taking photos and using a drone to film the area.
Sniffer dogs were also brought onto the site.
In a statement, Portuguese authorities confirmed the search had concluded on Thursday and that material collected would be handed over to the German authorities as they try to solve the mystery of what happened to Madeleine McCann.
A source close to the investigation said there was “nothing to report” after the search, which involved cutting back a vast area of undergrowth and using rakes and pickaxes, as well as sniffer dogs.
German prosecutor Christian Wolters added: “Of course there is a certain expectation, but it is not high.”
He said it was important to show that authorities were investigating the case.
The reservoir is about 31 miles from where Madeleine went missing during a family holiday in Praia da Luz in the Algarve on 3 May 2007.
She was just three years old.
“Of course we are still looking for the body,” prosecutor Mr Wolters said. “We’re not just looking for that, of course. There are other things too.
“Any discovery of clothing could help the investigation.”
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German prosecutors last year named Christian B an official suspect in Madeleine’s disappearance.
It is claimed the convicted child abuser and drug dealer used to visit the reservoir, allegedly referring to it as “his paradise”.
Christian B is currently in prison for raping a 72-year-old woman in the same area of the Algarve from where Madeleine went missing.
However, he has not been charged with any crime related to the British girl’s disappearance.
The new search was ordered after the Home Office gave an extra £110,000 to the Metropolitan Police to help with finding Madeleine, down from just over £300,000 last year.
More than £13m has been given to Operation Grange – the name of the investigation into her disappearance – since 2011.