A convicted paedophile and serial killer from Germany has emerged as a figure of interest in the hunt for missing Madeleine McCann, according to a former Portuguese detective.

Martin Ney, 48, who is serving life in prison for abducting and killing three German children between 1992 and 2001, is reportedly being investigated by officers from Portugal's Policia Judiciaria.

The 48-year-old child sex monster is said to closely resemble a photofit issued by detectives in the case and was understood to have been in Portugal in 2007, when the three-year-old was abducted.

Ney, who is in jail in his native Germany, has previously been interviewed by detectives investigating Madeleine's disappearance but has denied any involvement.

Originally from Hamburg, the predatory paedophile targeted children on holiday sometimes entering their apartments or tents wearing a mask and carrying a weapon and other times using camouflage in order to ambush them.