London (CNN) -- UK officers have identified 38 "people of interest" in connection with the disappearance six years ago in Portugal of British toddler Madeleine McCann, the Metropolitan Police said Thursday.
McCann disappeared while her family was on vacation on the Algarve coast in 2007. She was a few days shy of her 4th birthday at the time she vanished from the family's holiday apartment in Praia da Luz.
UK officers who have spent two years reviewing the initial investigations into her disappearance have found "new findings and new witness evidence," a police statement said.
"Our review has now progressed to a position where we have identified 38 persons of interest."
Twelve of those are UK nationals who the police believe were in Portugal at the time the girl went missing.
All the others are European nationals. Metropolitan Police officers are talking to authorities in other countries to get more information about them and their potential involvement, the statement said.
"We continue to believe that there is a possibility that Madeleine is alive," said Detective Chief Inspector Andy Redwood, who heads the team.
"It is a positive step in our hunt for Madeleine that our understanding of the evidence has enabled us to shift from review to investigation."
CNN's Richard Allen Greene contributed to this report.