Scotland Yard detectives have flown to Spain as part of their review of the Madeleine McCann case.
Officers spent three days with Spanish colleagues in Barcelona last month discussing the girl’s disappearance across the border in Portugal.
The Metropolitan Police force has said there would be no limits in its re-examination of the search.
Madeleine was nearly four when she went missing from her family’s holiday flat in Praia da Luz in the Algarve on May 3, 2007 as her parents Kate and Gerry dined with friends nearby.
Police have also travelled to Portugal three times in connection with the fresh review, the force said.
Detectives are unwilling to discuss what led officers to travel to Barcelona to meet Spanish police between November 23 and 25.
But a Scotland Yard spokesman said: “The review continues. There has been very good co-operation with Portuguese authorities and liaison will continue.
“We are not prepared to discuss specific details of these visits nor speculate about any future deployments to Portugal or elsewhere.”
Detective Chief Inspector Andy Redwood, the senior investigating officer, was understood to be among a team of detectives who went on the trips.
A total of 30 people are now working on the force’s Operation Grange.
The review prompted criticism when it was launched in May, with politicians expressing concerns that it would divert resources from other crime victims.
It was sparked after a request from British Home Secretary Theresa May supported by Prime Minister David Cameron.
Portuguese detectives, helped by officers from Leicestershire Police, carried out a massive investigation into Madeleine’s disappearance.
But the official inquiry was formally shelved in July 2008 and since then no police force has been actively looking for the missing child.