A primary school pupil has been raped in her bed by an intruder, police said yesterday.

Detectives, who would say only that the victim was between five and 10 to protect her anonymity, said she had endured "a nightmare ordeal". The attack took place between 9.30pm on Wednesday and 8am on Thursday at a house on the Craylands estate in Basildon, Essex.

The area is notorious for crime and vandalism and Tony Blair visited it last year to see how police were tackling the problems.

Appealing for help in catching the rapist, Chief Insp Graham Carey said: "We are dealing with a very young child here who has gone through a nightmare ordeal. This was an appalling, horrifying and utterly terrifying attack.

"It is very unusual for this type of offence to happen. At this stage we believe we are dealing with a stranger. The girl has told us she had never seen the man before. There is no sign of forced entry to the house and we are trying to establish if the doors were locked."

The child and her three siblings were in the house with their mother and two friends staying the night for a sleep-over when the attack occurred.

The rapist is described as black, aged between 18 and 20, of skinny build and with hair possibly in an Afro style.

The girl told the police that he had dirty teeth, with one distinctive clean tooth. He was wearing loose, ripped trousers with a belt and a metal chain hanging down to one side.

He had a grey top with lots of dark writing over it and may have been carrying a bag.

Mr Carey said: "The description has been provided by a very young girl who is obviously very traumatised by what has happened.

"We are in the process of gleaning information from the girl and the other children in the house but it is going to be a slow process." Officers trained in such sensitive inquiries were continuing to interview the children to try to coax more information from them as teams of forensic experts carried out an inch-by-inch search of the house and surrounding area.