McCann detectives ask for help from Portuguese cops

British police investigating the disappearance of Madeleine McCann have sent a third letter of request to Portuguese authorities.

Scotland Yard stressed that the document, sent on Friday, was a routine part of their inquiry but would not reveal what the letter said.

Madeleine McCann went missing from the ground floor apartment in Praia Da Luz on May 3 2007

The letters of request are the official channel through which British investigators can ask their Portuguese counterparts to carry out pieces of work on their behalf.

Deputy Assistant Commissioner Martin Hewitt said that so far no requests to carry out interviews or arrests had been made.