Officers received several complaints from
holidaymakers about a man they had seen behaving
strangely near Praia da Luz, where the McCann
family was staying.
The revelation will add weight to the theory that Madeleine was snatched to order by an international paedophile gang after being photographed by a "spotter".
In a separate twist, it has emerged that a
British yachtsman told police he saw Madeleine
on a Caribbean island in May.
Both developments are disclosed in newly
released Portuguese police files. Last week it
emerged British police were told Madeleine had
been abducted three days after being
photographed by a spotter.
According to the account in a Metropolitan
police email sent to the Portuguese and
Leicestershire forces, the picture was sent to a
child abduction ring in Belgium, which had
placed an order for a "young girl".
Having seen the image, the gang agreed that Madeleine should be taken. The files reveal that on May 9 last year ? six days after Madeleine disappeared ? officers interviewed Ernesto Mochacho, owner of a restaurant on Zavial beach, a 20-minute drive from Praia da Luz, which has a naturist area.
Mr Mochacho recalled seeing the McCann's with their three children for the last time at his restaurant in April.
His son, who also works at the restaurant, the only one on the beach, said he told police he had seen a "tall, thin Englishman in his forties" taking photographs.
"He was weird, a strange guy," Ivo Mochacho, 23,
told The Sunday Telegraph. He said police
visited the restaurant just after Madeleine
"Madeleine came here for lunch with her parents
not long before she disappeared," he said. "I
don't know if this guy took a picture of
Madeleine. It's impossible to say. But he took a
lot of photographs on the beach.
"The police said they had had complaints about a man acting strangely on the beaches. They thought he might have been a watcher, a voyeur. They told me to get in touch if I saw him again but I never saw him after that."
Mr Mochacho said members of the "Tapas Nine" ? the group of friends dining with Kate and Gerry McCann on the night Madeleine went missing ? were regulars at the restaurant, which has a terrace looking out across the Mediterranean. "They came a lot but I only saw the McCann family here once," he said.
The McCanns have long suspected that three-year-old Madeleine was abducted by a paedophile gang.
Last month police shelved their investigation and finally cleared the couple, both 40-year-old doctors from Rothley, Leicestershire, of involvement in Madeleine's disappearance.
Portuguese files also reveal Trevor Francis, a British yachtsman, told police he had seen Madeleine on the island of Margarita on May 16 this year.
Mr Francis, who is retired but owns a nursing
home in Worthing, West Sussex, and captains a
charter yacht, told police in a statement in
June: "I saw the little blemish in her right
eye. She really stood out. She was the absolute
of the missing Madeleine."
Mr Francis said he was having lunch at a restaurant in the town of Porlamar on Margarita, which is part of Venezuela, when the girl arrived with three women who looked Spanish or South American.
He said: "I was afraid to do anything. I decided to get a good look to make sure it was her so I could report it."
The girl looked healthy, but seemed "sullen and refused to eat", he said. His report has been sent to the Portuguese and Venezuelan authorities.