04/06/2014 09:15 BST | Updated 04/06/2014 09:59 BST

Madeleine McCann News: Police Probe Portuguese Scrubland With Ground-Penetrating Radar (PICTURES)

Officers investigating the disappearance of Madeleine McCann have begun using ground-penetrating radar equipment to probe for disturbed earth on scrubland near where she was last seen.

A man in plain clothes wheeled the device along a section of ground which was earlier cleared with strimmers in Praia da Luz on the Algarve.

On Tuesday officers in Metropolitan Police uniform were also seen carrying out a fingertip search at the same spot as they search for clues as to what happened to Madeleine, who vanished while on holiday in the resort in May 2007, aged three.

madeleine mccann search

Ground-penetrating radar equipment in use during the search for Madeleine McCann

The man spent a few minutes scanning the ground with the device over the small section of land, which is close to the police cordon.

It was then taken away out of sight.

British police officers accompanied by their Portuguese counterparts appear to be concentrating their investigations on the spot, which is close to the path and is strewn with rubbish, along with an area of the scrubland nearby.

The device uses radar pulses to take images of the subsurface of the ground.

It can be used to check for disturbance in a variety of substances, including rock, soil, ice and fresh water. It can also be used to detect voids and cracks in buildings and under pavements.

The large area of scrubland, just a few minutes' walk from the holiday apartment Madeleine was staying in with her family, is bordered by villas and town houses with one section alongside a road.

The site is dominated by a large mound in the middle where police have been parking their vehicles and officers stand watch with binoculars, monitoring the movements of the scores of press gathered below.

As well as the small section of land the radar equipment was used in, officers also appear to be focusing on a flat area to one side of the slope, where soil samples have been taken.

madeleine mccann

Madeleine McCann has been missing since 2007

Forestry workers were today continuing to clear away undergrowth from the spot, using strimmers to aid the search.

Officers have also been seen shovelling earth into buckets which has then been taken away for examination.

Small yellow marker flags poking out of the ground are being used to mark specific sites of interest while tape has been laid on the ground as police carry out their methodical search.

A number of small gazebo-style tents have been erected on the site, with officers on Wednesday putting one up over another area where fingertip searches were previously carried out.

Photo gallery Seach for missing Madeleine McCann See Gallery

They placed it on top of a spot where a piece of corrugated iron was discovered beneath undergrowth on Tuesday.

The metal is understood to have covered up a void in the ground. The piece of metal was then taken away by officers while men in Metropolitan Police uniform stood around in discussion.

On Tuesday it also emerged sniffer dogs used in the hunt for murdered schoolgirl April Jones have joined the search.

South Wales Police confirmed that two specialist dog handlers and victim detection English springer spaniels Tito and Muzzy were helping with the investigation.

Madeleine’s parents Kate and Gerry are not in Portugal but are being kept informed by Scotland Yard.

sniffer dogs hunt for madeleine mccann

A sniffer dog hunts through scrubland

Their lawyer Isabel Duarte said: “It is my belief that police have some very good information to be carrying out ground searches.

“I believe there is data in the file which has led to this operation because, if not, the police wouldn’t be performing this very drastic task.

“Kate and Gerry have not been given information that Madeleine is dead and until this happens they have to believe she is still alive.

“But they think police will come up with some significant news. It is such a stressful time for them."