A 15-year-old schoolgirl who disappeared 10 years ago was murdered by her father after falling in love with the wrong man, a court heard yesterday.

Tulay Goren became a "worthless commodity" in his eyes after she began a relationship he saw as inappropriate, jurors were told.

Her father Mehmet Goren killed Tulay "to restore the so-called honour" of his family, said Jonathan Laidlaw QC, prosecuting.

Tulay had fallen in love with a man called Halil Unal whom she met in the summer of 1998 at a clothes factory where her mother worked. She went missing in January 1999 and her body has never been found, the Old Bailey heard.

Mr Laidlaw said: "The circumstances in which Tulay was killed and the background to this murder demonstrate that Mehmet did not act alone in this offence because this was what has become known as an honour killing."

It is alleged that she was killed after Mehmet consulted with older brother Ali, the senior figure in the family, and younger brother Cuma.

Ali was in Workington, Cumbria where he ran a café on the day of the alleged murder while Cuma was closer at hand and appeared to have been involved in the disposal of the body, jurors were told.

Mehmet Goren, 49, of Navestock Crescent, Woodford Green, and his brothers, Cuma Goren, 42, of Evesham Avenue, Walthamstow, and Ali Goren, 55, of Brettenham Road, Walthamstow, deny murder-ing Tulay on January 7 1999.

They also deny conspiracy to murder her boyfriend, Halil Unal, between May 1998 and February 1999.

Members of the Kurdish family had arrived in Britain from Turkey in the early 1990s and claimed political asylum. Tulay, one of Mehmet's four children, was 12 when she came to this country. By the time she was 15 she had been "assimilated in London life" and attended Woodbridge High School in Woodford Green, Mr Laidlaw said.

He said that Tulay was often in trouble at school, while she had problems at home with her father, a part-time fish and chip shop worker, who gambled.

"What ultimately caused the most terrible of problems within this family and was ultimately to lead to Tulay's murder was a relationship she formed in London with a man called Halil Unal," Mr Laidlaw said.

"Despite their differences in age, Tulay pursued Halil. She clearly loved him.

"Tulay's father was outraged and was filled with a sense that his reputation and that of his family had been destroyed. Halil was viewed in every sense as an unsuitable boyfriend and potential husband."

Mr Unal, who was 30, came from a different town in the Kurdish region of Turkey and was brought up as a Sunni Muslim while the Gorens were from the Alevi branch of the faith, jurors heard.

Mr Laidlaw told the court that the discovery of the affair "would have produced in Mehmet a fear that she had lost her virginity and in his eyes would leave her as a worthless commodity in terms of his ability to marry her off".

In December 1998, Tulay told police her father had slapped her, then went to live with her uncle Cuma. A few days later Mehmet beat up Mr Unal and the day after Tulay ran away before turning up at Leytonstone police station, the court heard.

She said she had rowed with her father about her relationship and he had been violent towards her, Mr Laidlaw said.