A poster of Madeleine McCann in Praia da Luz. Photo: AP

Police searching for a British toddler abducted while on holiday in Portugal fear she has been snatched by a pedophile.

Officers said they had a prime suspect but were refusing to release any details, including a sketch, for fear of endangering Madeleine McCann's life. 

They believe the girl, whose fourth birthday falls this week, is alive and may be being held no more than five kilometres from where she was abducted. They fear they are now in a race to find her before she is murdered. 

Madeleine 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 on Saturday 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 abduction] down from the minute he approached them."

Senior officers have indicated privately that they suspect the motive for the abduction is sexual. Portugal's Judicial Police held a news conference on Saturday at which they denied being slow to react. 

Guilhermino Encarnacao, the director of the Judicial Police in the Faro region, said "many elements" 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 someone fitting a description.

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

Telegraph, London