Three-year-old Madeleine McCann has been snatched during a family holiday. Photo: AP

Portugal has ordered more police into the hunt for a three-year-old British girl believed kidnapped from a holiday hotel in the southern region of Algarve.

Members of the organised crime unit have been deployed to join the 240 police and fire officers and 20 civilians already searching for Madeleine "Maddie" McCann, Portuguese police said.

Police were scheduled to hold their first news conference later today, the first since McCann went missing.

The addition of the organised crime unit to the team highlighted fears that the girl might have been abducted by an international gang of sex predators, according to the Correio da Manha citing British and Portuguese investigators.

Another newspaper, Publico, said police were also looking into the possibility that Maddie might have been taken by an international adoption ring.

The girl disappeared from her hotel room in a seaside resort near the village of Praia da Luz in the Algarve on Thursday while her parents ate dinner at a nearby restaurant.

Early on Tuesday, investigators broadened the search zone for the missing three-year-old to 40 km around the hotel.

Reports said investigators had a photofit of the man suspected of kidnapping her, but they are holding it back out in fear of endangering Maddie's life.

According to a police description, the man was believed to be a pudgy British citizen around 35-40-years-old, of medium height, with a tanned complexion, and dark, slicked-back hair.

He was seen a week earlier in the southern Sagres region taking pictures of children. He had even tried to force one child into his car, according to the Publico daily.

Three British police joined the search on Sunday and were acting as a liaison for the parents, Gerry and Kate McCann, both 38-year-old doctors from Leicestershire in the English Midlands.

The Portuguese police were also in contact with the European police network Europol and its international counterpart, Interpol. 

AFP