Detectives in the Algarve were today expected to begin interviewing a number of key suspects in relation to Madeleine McCann, who vanished in Praia da Luz in 2007.
It has been suggested that UK officers could sit in on interviews carried out by Portuguese police with up to eight people who will become "arguidos", or people of interest, when they attend a police station voluntarily this week.
All are reportedly Portuguese nationals, although some being questioned are Russian-born, and have been identified by British police as being suspects.
It is thought they include three workers from the Ocean Club in Praia da Luz who have been linked to a string of burglaries in the area before the three-year-old's disappearance.
Neither the Metropolitan Police nor officers in Portugal would make any official comment on the reports.
Last month British officers, accompanied by their Portuguese counterparts, carried out searches of three areas of land near to where the young girl went missing.
She had been in a holiday apartment as her parents Gerry and Kate dined with friends nearby.
On finishing the latest search police said it had been the "first phase of this major investigation which has been agreed with the Portuguese".
A statement from Scotland Yard during the searches said there was "still a substantial amount of work yet to be completed in the coming weeks and months".
"This recent work is part of ensuring that all lines of inquiry are progressed in a systematic manner and covers just the one hypothesis that she was killed and buried locally," the statement said.
"This is the same as would be done in the UK for a murder or high-risk missing person inquiry."