It is the second time that Metropolitan Police detectives have flown to Spain as part of their review of her disappearance. Last month they spent three days with the Spanish National Police and Civil Guard force as part of inquiries into whether she was abducted and smuggled across the border from Portugal.
British detectives have also recently collected documents from the Portuguese police, Leicestershire police and the McCanns.
Yesterday Mr Marco said on Spanish TV: "We have provided [British police] with all the documents and information we have collated worldwide about Madeleine's disappearance." He told The Ana Rosa Programme: "[The leads] were passed at the time to Portuguese police who ignored them because it was a very politicised issue."
Madeleine, of Rothley in Leicestershire, disappeared from her parents' holiday apartment in Praia da Luz on the Algarve in Portugal in May 2007.
Her parents hired Metodo 3 to find her four months after she vanished.
The agency sent a team to Morocco to follow leads that she might have been smuggled out of Portugal.
Mr Marco said he still believed that was "very possibly" what happened to her but he refused to give more details.
The files taken by Scotland Yard include investigations the agency carried out into Raymond Hewlett, a convicted British paedophile who was in Portugal when Madeleine went missing and left for Morocco three weeks later.
Hewlett died of throat cancer aged 64 in Germany last year having refused to talk to detectives about Madeleine's disappearance.
Prime Minister David Cameron asked the Met to examine Madeleine's case in May. Operation Grange, led by Detective Chief Inspector John Redwood, will consider whether there are any grounds for the Portuguese police to re-open their original inquiry, which was shelved in 2008.
A spokesman for the Metropolitan Police refused to comment yesterday. The McCann family also declined to comment.
- DAILY MAIL