(CNN) -- An eight-day search in Portugal near where Madeleine McCann went missing seven years ago has uncovered no new evidence, British police said Wednesday.
London's Metropolitan Police -- also known as Scotland Yard -- are leading the hunt for Madeleine, who was a few weeks shy of her fourth birthday when she disappeared from her family's holiday apartment Praia da Luz, on Portugal's Algarve coast, in 2007.
Scotland Yard said its officers had been working alongside Portuguese police and experts to search specific areas in the resort town.
They had searched some 60,000 square meters of ground, including drains and derelict buildings, in what was "the largest deployment "ever undertaken by UK police overseas in a case of this type."
"The decision to search the 'horse shoe' shaped piece of waste ground to the west of Praia da Luz and other sites was as a specific result of the UK's investigation work to date," police said in a statement Wednesday.
"Forty-one ground anomalies were identified initially by both aerial survey and ground analysis which were then investigated fully," they said.
"At this time no evidence relating to Madeleine McCann has been identified. However it has given us an essential understanding of the activity on and people that have used this piece of land."
Scotland Yard said there was still a "substantial amount of work yet to be completed" in its investigation, and that "more activity" was expected to begin shortly.
"This recent work is part of ensuring that all lines of enquiry are progressed in a systematic manner and covers just the one hypothesis that she was killed and buried locally," it said.
Madeleine's parents, Kate and Gerry McCann, left the girl and her younger twin siblings asleep in the apartment on May 3, 2007, while they went for dinner with friends at a tapas restaurant nearby. Her mother checked on the children about 10 p.m. and discovered her daughter missing.
Last week, sources told CNN that British police were working on the assumption that Madeleine was dead, while their Portuguese counterparts were working on the assumption that she was still alive and had been taken out of Portugal by a non-Portuguese national who had been in the country for a short time.
Scotland Yard's head of specialist crime and operations, Assistant Commissioner Mark Rowley, told media on May 22 there would be "specific police activity" in Portugal in the coming weeks, relating to Madeleine's disappearance.
"It should not be assumed that this substantial upcoming phase of work in Portugal will immediately lead us to the answers that will explain what has happened," he warned at the time. "What you will see is normal police activity you would expect in any such major investigation."
Rowley also told media that Scotland Yard had made it clear to their Portuguese colleagues that they would not be giving operational updates, saying: "If media interfere with police work, that work will stop."
Scotland Yard reopened its investigation into Madeleine's disappearance in July 2013 after a two-year review of the original probe. Portuguese police reopened their investigation last October.
Madeleine's parents launched a massive publicity campaign to find their daughter and say they continue to believe she is still alive.
CNN's Isa Soares contributed to this report.