(LONDON) -- Police in Great Britain said they have identified new leads in the case of Madeleine McCann, the British girl who went missing in Portugal six years ago at the age of three.
Several persons of interest, as well as "both investigative and forensic opportunities" in the case, have been identified by Scotland Yard, authorities said.
Metropolitan Police said they were working with Portuguese police to determine the next steps, even though the missing girl's case is closed in the country.
"Our investigative review is ongoing and we are encouraged by the progress we are making," Metropolitan Police said in a statement, according to the BBC. "We are reviewing a significant number of documents and continue to identify potential lines of inquiry."
McCann was 3 years old when she vanished on vacation with her parents Kate and Gerry McCann and twin siblings in the Algarve region of Portugal. The girl's parents say they found Madeleine missing after having left the children in the home unsupervised while having dinner less than 500 feet away.
The review into the McCann case was opened last year after Prime Minister David Cameron responded to a plea from the girl's parents.
Kate and Gerry McCann have maintained a website and a 24-hour tipline to keep their daughter's case in the public eye.
On May 3, 2013, six years after Madeleine went missing, Kate McCann posted on the "Find Madeleine" website that the family was there "for the long haul."
"We still worry about her, we miss her as much as we ever did," McCann wrote. "We remain as determined as ever to find her and to know what has happened."
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