Specially-trained English springer spaniel Eddie and his companion Keela were taken to Praia de Luz complex in the Algarve several days ago as the search for the missing four-year-old intensified.

The police dogs, which are trained to sniff out minute traces of blood, were drafted in after the focus of the investigation again turned on the apartment where the McCann family were staying when Madeleine disappeared 97 days ago.

The dogs, which have also been involved in the Ulster search for missing Tyrone teenager Arlene Arkinson, were yesterday still in Portugal.

The identity of the two hounds emerged as reports that sniffer dogs from the UK found specks in the apartment where the four-year-old was last seen.

As Madeleine's parents Gerry and Kate last night clung to the hope that their daughter will be found alive, it is understood forensic tests are being carried out to determine whether the substance is actually blood.

If the tests prove positive, DNA samples could be used to see if there is any match to Madeleine.

Used across the world for his accuracy, seven-year-old hound Eddie helped police put Trevor Hamilton behind bars in 2006 after the victim recovery dog found 63-year- old Attracta Harron's blood on the 23-year-old murderer's burned-out Hyundai.

Eddie, who works for South Yorkshire police, also located Attracta's body in a shallow grave in April 2003.

Last year the dog and his handlers returned to Ulster for a third time to help find missing Arlene Arkinson.

The Tyrone teenager went missing after leaving a disco in Bundoran, Co Donegal, on August 13, 1994.

Both Eddie and Keela have also been used in various disappearance and murder cases in the US and the Republic of Ireland.

Despite the upsurge in activity, Kate and Gerry McCann have said that they are remaining focused on finding their daughter alive.