Police investigating the disappearance of British toddler Madeleine Mc Cann are trying to trace a serial sex offender.

Scotland Yard says the man assaulted a number of children on the Algarve between 2004 and 2006.

Detectives say the suspect may be linked to up to a dozen such crimes.

Madeleine Mc Cann disappeared while on holiday with her family in Portugal in May 2007.