Oxford gang members: (top left to right) Akhtar Dogar, Anjum Dogar, Kamar Jamil, Assad Hussain, (bottom left to right) Mohammed Karrar, Bassam Karrar and Zeeshan Ahmed who were found guilty of child sexual exploitation.

A victim of a gang of men who enslaved young girls for sex on the backstreets of Oxford has told how she and her mother repeatedly begged social services staff to rescue her from their clutches.

Speaking exclusively to the Guardian, the woman known in court as Girl C, the youngest victim to give evidence against the men, accused Oxfordshire county council of continuing to lie about the support it has offered to the victims of the gang.

She described how the gang began to abuse her when she was 13, plied her with crack cocaine and threatened to cut off the head of the baby she had by one of her abusers if she ever tried to escape them.

The woman spoke out as a jury at the Old Bailey convicted seven men responsible for running an underworld child sex abuse ring in the Cowley area of Oxford of 43 charges of rape, child prostitution, trafficking and procuring a backstreet abortion. Six victims gave harrowing evidence during the three-and-a-half month trial, but police believe the number of girls recruited by the gang and abused numbers more than 50.

The gang – who were of Asian and north African descent – targeted extremely vulnerable white girls as young as 11 on the streets of Cowley and sold them for £600 a time to be raped and violently abused over an eight-year period. Two other men were cleared by the jury.

A litany of failings by police and social services had allowed the men between 2004 and 2012 to groom young, vulnerable girls they met on the streets, outside schools and in cafes, entice them with the promise of alcohol and trinkets, and subject them over years to sexual atrocities and torture.

Girl C said that her adoptive mother went to social services in 2004 to beg for help. She said: “Mum wrote to all the key people in social services, called her own case conferences, invited agencies and got them sitting around the table, but they just passed the parcel between them – and all the while, I was getting increasingly under the power and influence of the gang.”

Two years later council agreed to put the girl in a temporary care home, but by then Girl C said: “It was too late: the grooming process had run its course. I was completely under their [the gang's] control.”

Shortly after she was trafficked from Oxford to London for the first time, Girl C said, she had tried to talk to staff at the care home but was told the conversation was “inappropriate”.

The seven men found guilty will be sentenced on 26 June. Judge Peter Rook QC told them: “You all understand that you’ve been convicted by the jury of the most serious offences. Long custodial sentences are inevitable.”

It is understood that the police investigation is ongoing and a number of other individuals are suspected of being involved in an organised criminal gang trading in children. Seven men are on police bail, and more arrests and police raids are likely in the coming weeks, while Girl C also said that young girls were still being groomed, abused and trafficked by local gangs operating in the city.

The abuse echoes child sexual exploitation rings in Rochdale, Derby and Telford, where gangs of Asian men groomed young white girls for sex and prostitution. Victims were subjected to abuse that went on for days and involved the use of knives, meat cleavers and baseball bats. One girl was forced to undergo an illegal abortion at a backstreet clinic when she became pregnant by one of the abusers.

Professor Jenny Pearce of the University of Bedfordshire, said: “We cannot ignore that there is a model that exists where some white young women, who appear to be available and who appear to be vulnerable, can be preyed on by groups of Asian men of Pakistani origin who might be looking for sexual favours or who are linked to organised crime like drugs and who target these young women. But that doesn’t mean … they are the only type of victims.”

The men found guilty – Mohammed Karrar, his brother Bassam, Anjum and Akhtar Dogar, Zeeshan Ahmed, Kamir Jamil and Assad Hussain – all came from the Cowley area of Oxford and included two sets of brothers. They were well known in the area, attended the local mosque and had wives and children of their own. They were convicted of 43 offences over eight years, from 2004 to January 2012, involving six girls who were aged 11-15 years old at the time.

Mohammed Hussain, 25, was cleared of three counts of sexual activity with a child. A ninth defendant, who cannot be named, was cleared of a similar charge.

Victims turned to the police at least six times – four times in one year – but investigations were begun and then halted when the vulnerable girls withdrew complaints. One girl was threatened by the police that she would be charged with wasting police time over her repeated absences from a childrens’ home.

Sara Thornton, the chief constable of Thames Valley police, said: “I am very sorry this case took so long to get to court and I have said so to all the young women.”

Joanna Simons, the chief executive of Oxfordshire county council, added: “We are incredibly sorry we were not able to stop it any sooner. We were up against a gang of devious criminals. The girls thought they were their friends.”

But Girl C remains unhappy with the council, criticising the single offer of help she says she received. She said: “The council put out a press release claiming they had offered wraparound care to all the girls and their families, but the first we heard from them in five years was a letter on 13 April from Jim Leivers [director for children, education and families at the council], where he says he’s been ‘closely involved in providing support’ to me.

“That’s a complete lie. My family have had no support or offers of help at all from Oxfordshire. Nothing. Not at any point. Not even a phone call. The last contact we had with the council was five whole years ago, when my mum was begging them to help her stop me go off the rails. They ignored her then and they’ve ignored us since.”

A spokesman for the council said: “We are sorry the abuse was not stopped sooner. One of the elements of the serious case review will be an investigation of the support offered to the girls by agencies including social services.

“Our offer of a meeting with Girl [C] and her family was very sincere and similar offers to the other girls have been accepted. We want to do everything we can to help all the girls rebuild their lives and our door is open to Girl [C] and her family,” he said.

The abuse was only exposed when a police officer proactively went out to build evidence against the men in 2010. Simon Morton, then detective chief inspector, put the men under surveillance, traced their phones, pulled every social services record of missing girls in Oxford who he thought were victims.

He said: “This was happening in Oxford – the city of dreaming spires. If it was happening there, the ramifications for all cities are huge.”