British police have appealed for holiday photographs to help identify the person who abducted Madeleine McCann.

Officers are interested in any images taken at the Ocean Club resort or surrounding area in the Algarve in the two weeks before the four-year-old went missing.

The pictures will be run through a cutting-edge facial recognition program and cross-referenced against a database of suspects.

Police say they want digital images, which include strangers in the background and not family shots or panoramic photographs of empty scenery.

The submitted photographs will then apparently be cross-referenced against a database of images of British pedophiles and other criminals.

A special Web site been launched to receive the anticipated deluge of images.

A British photography shop, Jessops, will convert traditional prints to digital images for free.

In Praia da Luz, Madeleine's mother, Kate McCann, observed an unofficial minute's silence at midday.

Tourist Catherine Morrison, 59, of County Cork, was among those to fall silent in a Praia da Luz supermarket.

"It was a brilliant idea to show respect for the family and friends and relatives," she said.

Madeleine's father is in Britain for his first visit home since his daughter was abducted 18 days ago.

Gerry McCann is using the trip to meet organizers of the Find Madeleine fund and attend to personal matters — in preparation for an expected prolonged stay in Portugal.

He is expected to visit the main square in his home village of Rothley, Leicestershire, where thousands of well-wishers have tied yellow ribbons.

It is the first time he has been apart from wife Kate and two-year-old twins Sean and Amelie since Madeleine was taken from their Algarve holiday apartment.

The McCanns have said they are convinced their daughter is still alive and have vowed to stay in the Algarve for the foreseeable future, coordinating an international campaign to get her back.

They are believed to be considering a round-Europe mission to spread awareness of Madeleine's abduction in the hope that she will be found.

The findmadeleine Web site, which carries a diary from the McCann family, has now received almost 100 million hits.

That does not mean 100 million people have visited the site. Every Web page download from a Web site may contain multiple files that are included in the hits figure.