More than a dozen Somali men have been convicted of running an inner city sex ring where vulnerable British girls as young as 13 were abused, raped and forced into prostitution in the latest appalling case of organised abuse to blight yet another city.

Gang members used colourful nicknames such as Left Eye, Magic and Trigger to impress teenage girls in Bristol who were groomed for so long they believed sexual abuse was simply another part of a loving relationship they thought they had with the men.

The victims were passed around the gang’s friends for as little as £30 or "rewarded" with alcohol, drugs or gifts to perform sex acts on older men in a horrifying catalogue of abuse with echoes of cases already effecting Rotherham, Rochdale, Oxford and several other areas across England.

In perhaps the worst incident one 13-year-old girl was raped four times by three different men having been trafficked across the city to a Premier Inn by one of her abusers. Police were alerted to her plight in December 2012 but the girl feared for her life so initially refused to speak out.

In May 2013 Avon and Somerset police launched Operation Brooke after a 14-year-old girl was found hiding in her underwear in a cupboard under a sink at a flat in Easton where her older sister was the tenant. A council outside Bristol who placed the older girl there on her own was heavily criticised by the judge as the property was taken over as a sex and drugs den by the gang who abused the sisters and another of their friends. She had befriended the Somali men after buying cannabis from them and it was not long before the gang were using her flat to sell drugs and have sex with her.

The local authority, which cannot be named, launched a serious case review to discover why the girl, described as having a chaotic life, had been left almost unsupervised by social workers even though staff had “very real concerns” about her. Officials tried to persuade the teenager to leave Bristol but the girl refused and because she was under a Section 20 care order, also known as voluntary accommodation, the council could not force her to leave.

Fourteen Somalis aged between 20 and 24 were convicted in two separate trials of charges including rape, sexual activity with a child, facilitating child prostitution, trafficking, paying for the sexual services of a child and drug offences.

Some of the victims in Bristol were persuaded to have sex with their boyfriends' friends as it was Somali “culture and tradition” and “men always have sex with each other’s girlfriends”. Legal restrictions were lifted today to allow reporting of both trials.

Liban Abdi, aka Left Back, 21, Mustapha Greens Farah, 21, Arafat Left Eye Osman, 20, Idleh Sniper Osman, 22, Abdulahi Trigger Aden, 20, Said Zakaria, 22, Mustafa Deria, 22, and Deria’s cousin Mohamed Magic Jama, 20, were all jailed for between 18 months and 13 years for either child sexual exploitation or drugs offences in the first trial at Bristol Crown Court.

Judge Michael Roach spoke out at the conclusion of the two-month trial questioning a decision which led to the girl being raped and prostituted by Somali drug dealers.

Convicting the men Judge Michael Roach said: “I know that the drug trade in Bristol blights many parts of the city. It ruins the lives of many, not just the users but also their families and their dependants. It has been said many times before - and it is true - it is a filthy trade.”

Referring to the 16-year-old girl he said: “She was a very troubled girl. Save for limited supervision she was left to her own devices without the support of her family and friends. She didn’t know Bristol or the city at all. On the evidence she was very isolated. Consequently within a day or two of her arrival she fell prey to these defendants and their associates.

“They took considerable advantage of her. I hope there will be an opportunity for the authorities to reconsider their thinking behind such a placement because it has, on any retrospective view, added considerably to the damage of that young person."

Judge Roach added: “Girls of her age, whatever their experience, need the protection of the law. The treatment of her in my judgement was extremely serious.”

The girl’s five-month ordeal finally ended when police arrived at the house looking for a 14-year-old runaway – known as Girl B for legal reasons – who had gone to the flat because she her the sister, identified as Girl A, was the tenant.

Ms Vigars said: “[Girl B] was very upset, in tears, with her makeup running down her face. She said to the police ‘they made me do stuff’. She said that one of the men had forced himself on her, he had raped her.”

Girl A described to detectives one occasion where she had sex with a man who later refused to pay. She said: “Sometimes I couldn’t even be bothered to fight or argue for it because it’s hard to tell them at the end of the day ‘No I don't want to do it’ but half the time I did.

“Half the time I didn’t really want it for the money, I just wanted someone to be there. Even though I know they were using me for sex and that, sometimes it’s just nice to be close to someone, do you know what I mean?”

Zakaria, whose nickname was Target, and six other men - Mohamed Jumale, 24, his brother Omar Jumale, 20, Mohamed Dahir, 22, Jusuf Abdizirak, 20, Abdirashid Abdulahi, 21 and Sakariah Sheik, 21 – were convicted of the grooming and subsequent sexual abuse of four young girls in Bristol at the second trial. They will be sentenced on Friday. Two defendants, Jibril Mohamed, 21, and Dauud Osman, 19, were acquitted.

The chair of Bristol Somali Forum Muna Ali said she was “shocked and saddened” by the “evil” abuse. She said: “There are a lot of cases going on across the country. This case is no different. I am hoping people will look at this as a crime and not just a crime for the Somali community. I would love for you to look at it as criminal, not Somali criminal. The community is deeply shocked and shaken by the outcome of this case. They are unforgivable acts of cruelty against the most vulnerable members of our community.”

Anna Vigars, prosecuting, told the jury in the second trial: “Some of those girls knew each other, some didn’t, some had heard of each other. But what these girls have in common is that they were used by these men for sex.

“It is about the defendants simply using the girls to satisfy themselves whenever they felt like it, doing it so often that no doubt it began to feel normal as far as these girls were concerned. There are elements of exhibitionism too with sex taking place in front of other people in the group. Much of it is sordid, none of it is romantic.”

One victim was 11 years old when Mohamed Jumale first began grooming her after the pair met on Facebook. She lost her virginity to Jumale before he ordered her to have sex with his brother Omar and two other men under a bridge by a B&Q car park in Bristol.

The girl described how she would go to the house in Easton with a girlfriend because “we had nothing else to do” and met Zakaria, who claimed he was 14, on a number of occasions.

She told the court: “When I first meet people I am always a bit scared and this time it was me and my friend and we were in a room with six other boys. It was a bit scary.”

The girls went to the house on around 20 occasions from October 2012 and would listen to music, smoke cannabis, chew the stimulant khat, which is popular in the Horn of Africa, and chat with the men.

Her friend, who was a prosecution witness, would smoke cannabis, though the girl did not, and have sex with men in the house, Bristol Crown Court heard. All the girls were able to give evidence via videolink so they did not have to face their abusers in court with volunteers from the court’s Victim Support unit to support them.

The girl said: “I think sometimes they might have been getting money from having sex from her. If they would run out of weed that’s when she would have sex with them. That’s when they would get weed.