THREE men and a 17-year-old youth have gone on trial accused of grooming and sexually exploiting vulnerable girls under-16.

The group is accused of befriending the girls before using threats and intimidation to get them to have sex.

A jury at Teesside Crown Court was told seven girls - one aged 13, five aged 14 and one aged 15 - were manipulated and abused by the men.

Outlining the case for the prosecution on the first day of their trial, Christopher Knox said the case involved the exploitation of a group of young girls by a loosely connected group of young men.

He added: "These are sexual activities with girls who are almost without exception vulnerable for one reason or another and who have, in almost all cases, been groomed by these young men and sometimes passed around from one to another.

"The prosecution say this is not a girlfriend boyfriend relationship - it is an exploitative relationship which we call grooming."

Shakil Munir, 32, of Tollesby Road, Middlesbrough, is charged with four counts of sexual activity with a child and child abduction against two girls aged 13 and 14.

Junaid Butt, 18, of Kensington Road, Middlesbrough, is charged with sexual activity with a child and arranging or facilitating commission of a child sex offence. His two alleged victims were aged 14 and 15.

Ibrar Mahmood, 18, of Breckon Hill Road, Middlesbrough, faces four charges of sexual activity with a child and three of causing or inciting a child to engage in sexual activity. The charges relate to two girls both aged 14.

The 17-year-old male youth, who cannot be named for legal reasons, is charged with three counts of arranging or facilitating commission of a child sex offence. His three alleged victims were aged 14.

A fifth defendant, Sakib Ahmed, 18, of Cambridge Road, Middlesbrough, has admitted five charges of sexual activity with a child. The charges relate to five girls, one aged 13, three aged 14 and one aged 15.

The court heard the girls had been given cannabis and free cigarettes by some of the men, who used Facebook, as well as Blackberry and MSN messaging, to keep in touch with the girls.

The jury was told one defendant, 32-year-old Shakil Munir, had got to know two of the girls after picking them up in his taxi.

He later collected a 14-year-old girl in the middle of the night while she was still wearing her pyjamas, slippers and dressing gown, Mr Knox said.

The barrister added than although the girl though they were going to buy cigarettes, the defendant drove her to a lay-by near Stokesley.

He then asked for oral sex, but when the girl laughed at him he threatened to throw her out of the car, Mr Knox said.

In a separate incident, Ibrar Mahmood is alleged to have a pinned down a 14-year-old girl and demanded she gave him oral sex.

The jury was told the defendant had also threatened to tell the girl's boyfriend about their sexual relationship unless she did as he wanted.

Junaid Butt is alleged to have kept one girl's friend out of the way while his friend, Sakib Ahmed, could engage in sexual activity with her underage friend.

The court heard that Mr Ahmed allegedly told a 14-year-old to "pretend" she was 16 when they met at an under-18s disco at The Vault, in Stockton.

Prosecutors say all defendants knew the girls were under 16, with one girl asking a defendant to take her to school and another appearing on her Facebook profile in her school uniform with her date of birth also visible.

All five defendants deny all charges.

Judge John Walford told the jury that comparisons could be drawn with similar cases which had prompted public debate, however he urged them to try the case on the evidence.

The trial is expected to last up to four weeks.