Gerry and Kate McCann with their twins as they awaited news of their daughter Madeleine's disappearance

Local Britons and holidaymakers help comb Praia da Luz for clues to help find Madeleine

Police searching for Madeleine McCann, the British toddler abducted while on holiday in Portugal, fear she has been seized by a paedophile.

Officers have a prime suspect but were last night refusing to release any details, including a sketch, for fear of endangering Madeleine's life.

They believe the girl, whose fourth birthday falls this week, is alive and may be being held no more than three miles from where she was abducted. They fear they are now in a race against time to find Madeleine, known as Maddy, before she is murdered.

She vanished between 9pm and 10pm on Thursday night from her room at a holiday complex in Praia da Luz, a fishing village on the Algarve, as she slept between her twin brother and sister, aged two.

Their parents, Gerry, a consultant cardiologist, and Kate, a part-time GP, both 39, were eating with friends at a tapas bar a minute's walk away.

More than 150 people were involved yesterday in the hunt for Madeleine, as tensions grew between the family, from Rothley in Leicestershire, and Portuguese police over the way the investigation has been handled.

Speaking from Glasgow, Philomena McCann, Madeleine's aunt, accused police of being uncommunicative and said: "My brother is at his wits' end. They have just played [the disappearance] down from the minute he approached them."

She said that Madeleine "is the centre of her parents' universe, she is an integral part of the family, a big sister. She is the Pied Piper, the little princess, the focus of every day for the parents. I cannot understand why anyone would do such a wicked thing to this family."

Senior officers have indicated privately that they suspect the motive for the abduction is sexual. Portugal's Judicial Police, the equivalent of Britain's CID, held a press conference yesterday at which they denied being slow to react.

Guilhermino Encarnacao, the director of the Judicial Police in the Faro region, said there were "many elements" which pointed to an abduction but he refused to give even the sex of the suspect. He also declined to indicate whether his men were looking for a named individual, or simply someone fitting a description.

Mr Encarnacao said police believed Madeleine was still alive and that airports in Portugal and neighbouring Spain had been alerted. Police had received more than 30 calls with possible new lines of inquiry, all of which were being followed up.

Asked about claims that a British man had reported seeing a child with two people, Mr Encarnacao said this was one of the many pieces of information being investigated.

There was confusion yesterday over early reports that there had been a break-in at the McCanns' two-bedroom, ground-floor apartment at Ocean Club, a resort run by the Mark Warner travel company.

Trish Cameron, Mr McCann's sister, said on Friday that she received a telephone call from her brother, who was "hysterical and crying his eyes out".

She said: "They had put the kids to bed at 7pm and checked on them every half-hour as they had dinner nearby with the rest of the party. Gerry said the window was open, the shutters broken and the door, which had been locked, was hanging open."

But Robin Crossland, the administrator of the resort said he had been present when the McCanns were first interviewed by police soon after Maddy vanished. "They clearly said that they had left the French windows unlocked as they were using them to access the apartment to check on the children throughout their meal," he said

On Friday night, Mr McCann appealed to his daughter's abductor: "Please let her come home to her mummy and daddy, her brother and sister."

Mark Warner operates a drop-in creche during the evening, but it is understood the McCanns opted to leave their children - all conceived through IVF - in their apartment so they would get a proper night's sleep, and then check on them regularly throughout the evening.

Brian Kennedy, who is Maddy's great-uncle, and his wife, Janet, attended a prayer meeting at Rothley Parish Church, close to the McCanns' home. "We fear the worst but we are hoping for the best," he said.

Portuguese police have a mixed clear-up rate with missing person cases, while sex crimes are on the increase. Currently, 75 people remain unaccounted for, seven of whom went missing as children, according to the police website.

A two-year-old girl, Sofia Andrade de Oliveira, was snatched from home in Madeira three years ago and still has not been located.