British police want to deepen the genetic and biological examinations carried out when Madeleine first disappeared in 2007, Francisco Brizida Martins was quoted as saying by Portuguese media agency Lusa after meeting inspectors from London.

Technical advances "today allow us to go further than a few years ago", Brizida Martins said, adding that the new analysis could be conducted either in England or at his own medical facility in Coimbra, central Portugal.

Scotland Yard inspectors returned on Monday to the southern city of Faro to begin fresh interrogations of suspects after calling for a new push by local investigators in the high-profile case in August.

Madeleine disappeared from her bedroom in a hotel complex in Praia da Luz, a resort in the southern Algarve region of Portugal, on 3 May 2007, then aged nearly four.

Portuguese police closed their search in 2008 after 14 months of controversial investigations, which at one point implicated Madeleine's parents in her abduction before their names were cleared.

After two years studying the case, Britain officially opened its own investigation in July last year and the Portuguese authorities reopened their case shortly after.

AFP