The parents of Madeleine McCann say they are prepared to take a lie detector test to prove their innocence.
Kate and Gerry McCann's move is the latest stage in a high-profile fightback against police suspicions they may been responsible for four-year-old Madeleine's death in Portugal in May and staged an elaborate cover-up.
The McCanns were declared "arguidos" or official suspects, by detectives two weeks ago after DNA traces in a car hired after her disappearance were used to suggest the vehicle had been used to carry Madeleine's body.
The couple have returned to Britain after a four-month stay in Portugal and have been told that police do not have enough evidence to justify interviewing them again.
But the McCanns, who remain suspects, say they are determined to clear their names and continue the search for Madeleine.
It emerged this week that partial DNA matches found in the Renault Scenic hired by the family almost a month after her disappearance could potentially be explained by contact with Madeleine's clothes, which were transported in it when they moved to a rented villa.
PA