British investigators began searching Tuesday with sniffer dogs on scrubland in Praia da Luz, Portugal, for more clues into the disappearance seven years ago of Madeleine McCann. 

The dogs, which were brought to Portugal from the U.K., were searching the area, just a few blocks away from the apartment from where the little girl disappeared in 2007, just before her fourth birthday, as police teams from both countries participated in the search which could involve ground penetrating radars and excavation machines later in the week.

hi-mccann-double.jpg

Composite photos showing three-year-old Madeine McCann, left, with a computer generated age progression image of the missing child as she might look now, right, issued Thursday July 4, 2013. (Metropolitan Police, Teri Blythe, Associated Press)

The current search is the result of a request by Scotland Yard to Portuguese police. The area was searched in the days following her disappearance.

Officers placed yellow-and-white police tape around the waste ground, which is larger than a soccer field and covered in bushes and some trees. They were expected to conduct a forensic examination of the area in coming days. 

New searches in coming weeks

Officials made no immediate comment on this week's developments. Cases that are under investigation in Portugal are covered by a judicial secrecy law, which forbids the release of information. 

Madeleine McCann map

Police are searching an area 300 metres from the apartment at the Ocean Club resort in Praia da Luz, Portugal, where Madeleine McCann was last seen. (CBC News)

Authorities in Portugal and Britain said recently they would conduct new searches in coming weeks after reviewing the case file and a new public appeal for information.

Portuguese police closed the case in 2008 because authorities had detected no crime. The public prosecutor's office in Lisbon last year reopened the investigation, saying new leads emerged during the case review though it did not elaborate.

British police launched Operation Grange in 2011 to try to find out what happened to Madeleine. British detectives have been sifting through the Portuguese case files and say they have identified new avenues of investigation. Among other things, they have compiled a record of cases involving sexual assaults on children in the area between 2004 and 2010.