Portuguese police have said they cannot be certain missing three-year-old Madeleine McCann is still alive.
Chief Inspector Olegario Sousa said the question was "very difficult" to answer "because I have not facts to sustain that the child is alive or not".
Madeleine, of Leicestershire, is feared to have been abducted from a holiday apartment in the Algarve village of Praia da Luz in Portugal on Thursday.
Her mother Kate appealed to whoever was holding her daughter not to hurt her.
"Please do not scare her. Please let us know where to find Madeleine or put her in a place of safety," she said.
Police said they had widened their search to nine miles (15km) from Praia da Luz and were working closely with Interpol and Europol.
Ch Insp Sousa said: "We're searching for the child and until the moment she appears we can say nothing more because we are not magicians."
He added that it was not possible under Portuguese law to give further details.
Ruins, wells, bushes
Dave Shelton from Manchester, who now lives in the village, has been co-ordinating volunteer searchers.
He told BBC News that each morning a group of up to 20 locals and tourists searched an area around the village, concentrating on ruins, wells and bushes.
"Every morning at eight I go to see the police chief and he decides where we go and gives us our little zone, plus a map.
"We go off and do that area and then report back and tell him we have done the area so he can tick it off."
Mr Shelton added: "I have two young children as well and I would like to think if I was in a foreign country that the people would help out as well and help find the child."
Villagers in Rothley, where the McCanns live, are holding a silent vigil for the family and people are being encouraged to light a candle or to tie a red ribbon around railings at the War Memorial on the village green.
Staff at Leicester's three hospitals are also joining in prayer for the McCann family.
Madeleine's father Gerry is a consultant cardiologist at the city's Glenfield Hospital.
Mrs McCann, who had asked to speak to the media, said on Sunday: "We would like to say a few words to the person who is with our Madeleine, or has been with Madeleine.
"Madeleine is a beautiful, bright, funny and caring little girl. She is so special. Please, please, do not hurt her.
Her final sentence was in Portuguese - "Por favor, devolva a nossa menina" - which means "Please give our little girl back".
Madeleine's family have confirmed that when she disappeared she was wearing white pyjama bottoms with a small floral design and a short-sleeved pink top with a picture of Winnie the Pooh character Eeyore.
She is believed to have been taken from her bed while her parents were eating at a nearby restaurant and regularly checking on her and their two-year-old twins Sean and Amelie.
Around the marina in the nearby town of Lagos, maritime police have been searching amid claims a man was seen with a small girl in the area.
Police had said on Saturday they thought Madeleine had been abducted but was alive.
Madeleine has not been seen since Thursday night
They have said they are not able to publish an artist's impression of a suspect because they feared it may harm the case.
Mrs McCann found the outside shutter and window to Madeleine's room had been opened and her daughter missing shortly before 2200 local time on Thursday.
Earlier local mayor Julio Barroso told BBC News 24 about 130 people were working on the case, including 80 detectives, some of whom had come from the capital Lisbon.
The resort where Madeleine disappeared