UK prosecutors have written to the Portuguese authorities seeking help with the British inquiry into the disappearance of Madeleine McCann.
It is the second international letter of request to be made and comes amid reports that police are poised to make their first arrests.
According to reports, British police want to question three burglars who were operating in the Portuguese resort of Praia da Luz where Madeleine disappeared.
A spokesman for Madeleine’s parents Kate and Gerry said the letter was “a significant development”.
“It is necessary for British police to request the Portuguese authorities allow them to operate on their turf.
“It means they have the intention of arresting and interviewing X, Y or Z. We don’t know who they have their sights on but it’s likely it is the burglars.
“Whether the Portuguese will co-operate remains to be seen. It is a very sensitive issue with differences they have had.
“Police want to be given a chance to arrest key suspects. It doesn’t prove they have Madeleine but it will rule them in or out of the investigation and that is important.
“Kate and Gerry don’t want to build up their hopes too high but they realise it could be a significant new lead.”
The Crown Prosecution Service (CPS) and Scotland Yard have not commented on the detail of the latest letter to the Portuguese, apart from confirming it was sent last week.
Madeleine, who was then nearly four, disappeared from her family’s holiday apartment in Praia da Luz in the Algarve on May 3 2007 as her parents dined at a nearby restaurant with friends.