By Rachel Younger, Sky News Correspondent
British police are looking at five new cases in which young British girls were sexually abused during holiday home break-ins by an intruder in the Algarve.
One of these assaults took place on a 10-year-old girl in Praia da Luz, from where Madeleine McCann vanished two years later.
These new cases are similar to some of the originally identified twelve offences where a male intruder gained access to holiday villas occupied by British families in the Western Algarve.
Scotland Yard recently made an appeal to trace the intruder which lead to 500 people contacting them with new information.Madeleine disappeared from her bed in Praia da Luz in 2007
Detective Chief Inspector Andy Redwood said today: "We have now identified a further five sexual assaults and one near miss. None of those six matters we were aware of prior to our appeal.
"In this new tranche of information we have got one crime which is very clearly in the heart of Praia da Luz in 2005, on a young, white, 10-year-old girl.
"Clearly the fact that we've now got an assault that is in the heart of Praia da Luz, very close to where a previous matter had been reported, means that we are even more interested in this as part of the inquiry."
In four of these incidents the man sexually assaulted five white girls, aged between seven and 10, while they were in their beds.
Although Portuguese police have turned down requests for a joint investigation, British police added they are poised to begin operations in Portugal following an official agreement from Portuguese police later this week.Police are still keen to trace a man seen near Madeleine's appartment
Metropolitan Police Deputy Assistant Commissioner Martin Hewitt said he is "cautiously optimistic" Portuguese and British officers can act soon.
"I am cautiously optimistic that in the not-too-distant future we are going to start to see activity," he said.
Officers have so far identified a series of 18 crimes committed between 2004 and 2010 where a male intruder entered villas occupied by UK families on holiday in the Western Algarve.
Twelve of these are assaults which took place between 2004 and 2010, although the vast majority happened before Madelaine's disappearance. All involved girls aged between 6 and 12 years old.
Police believe the suspect may have been in the villas for some time before being disturbed by parents or a child waking up - and he remained calm even when interrupted.
The noise of a bin collection lorry was heard nearby on two occasions.
The suspect is described as having tanned skin with short, dark, unkempt hair.
Police are still hunting a man seen carrying a girl fitting Madeleine's description on the night of her disappearance.