A teenage boy has told a Court how an au pair bit him on the shoulder, beat him with a belt and twice assaulted his three-year-old brother.

And the youngster's tearful mother claimed that after being picked up by police, Hungarian Zsolt Vamos later sent her a letter saying she had played a "dangerous game" and demanded £10,000 from her.

Bradford Crown Court heard of five alleged attacks on the boys during Vamos's nine-day stay at their home in the Bradford area.

The 23-year-old also faces charges of leaving the family's five children home alone when he and another au pair walked out on them in September last year. The family can't be identified for legal reasons.

In a video-taped interview, the 13-year-old detailed incidents of abuse to the courtroom.

He claimed that on one occasion, while he was trying to teach his young brother chess, Vamos walked up behind him and bit him on the shoulder for no reason.

And after he spotted Vamos banging the three-year-old's head against a bed frame, the youngster told how the au pair turned on him, slapping him around the head. Vamos was also said to have struck the teenager up to six times with a leather belt after he saw him throwing his brother on to a bed, breaking a slat.

"He just pushed me on the floor," said the teenager.

"I was on my knees and he just started belting me on my back."

The boy, who cannot be named for legal reasons, added: "He kept me down on the floor while he was belting me.

"I was trying to get away."

The court heard Vamos spoke little English when he arrived and the teenager admitted that he didn't really like him from the start.

The boy's mother broke down in tears as she recalled him showing her bruises on his thighs from Vamos's alleged attack. And she described going "crazy" when he pointed out the broken bed where Vamos had thrown the three-year-old on to it.

Months later, after police interviewed the Hungarian, she told how she had received a letter from him and added: "I was very frightened."

Simon Keeley, prosecuting, read out the note, which was written in broken English.

It said the woman and her husband had "played a very bad and dangerous game" and added: "I am writing the rules to this game."

It demanded £10,000 "for the libel and the many problems you have caused me" otherwise Vamos would take them to court where they would lose their house, Mr Keeley said.

Andrew Woolman, defending Vamos, said that at the time of the allegations, the couple were already having a "big battle" with the agency which supplied him.

She admitted that she did not want Vamos there at all because she had asked for a female who spoke good English. The court heard how the couple e-mailed the firm ordering them to "remove him immediately" and also telling them to pay £100-a-night for his accommodation there.

Mr Woolman said there was a "hysterical atmosphere between the parents and the agency" and that their children may have picked up on this.

Vamos, of Capel Road, Ruper, Sussex, denied three charges of common assault against the 13-year-old and two against his three-year-old brother. He also pleaded not guilty to child cruelty charges relating to the five children being left home alone. Vamos also denied intimidating a witness through the letter.

The prosecution originally claimed the five children may have been left home alone for an hour when the au pairs walked out. But in court, the youngster indicated that his mother arrived home as they were leaving.

The trial continues.