A Nato spy plane may have captured the kidnap of Madeleine McCann from Praia da Luz on film by accident, according to a military expert.
According to Philip Burden, a military plane was taking part in a training mission which passed over the Portugese coastline on the day the British three-year-old vanished from the beach resort, in May 2007.
Images from the exercise were taken on a military-grade camera, sharp enough to make out buildings and faces, even in the fading light of the day.
Burden said snaps from the day were passed on to the Portuguese police by the country's Air Force, but were nowhere to be found when classified files were published later.
"It was on a Nato training exercise and had been used on similar missions over other European countries at other times," Burden told the Express.
"I'm told that there were a number of low-level passes over the resort as part of a lengthy photo reconnaissance training mission. Although the light was fading, people and buildings could be clearly seen.
"According to my source, strips of film were later passed to the Portuguese police following their appeal for information about Madeleine's disappearance."
There was no comment from Metropolitan Police on whether aerial photos taken by a Nato plane were being pursued as a line of inquiry. A Scotland Yard spokeswoman said: "We are not prepared to comment on an on-going investigation."
Portuguese police reopened their inquiry into McCann's disappearance this year, after it was shelved in 2008 - a year after she went missing.