A girl was smuggled into Britain from Somalia so organised gangs could harvest her organs for transplant surgery.
The shocking case emerged after a report showed that the number of reported human trafficking victims in the UK has risen by more than 50% over the last year.
The number of women being trafficked to the UK rose by 12% to 786 and the number of men increased by around 30% to 400.
Child protection charities have warned that the case is not an isolated incident, saying that criminal gangs are attempting to exploit the demand for transplant organs in this country.
Bharti Patel, the chief executive of anti child-exploitation charity Ecpat UK, told the Daily Telegraph: "Traffickers are exploiting the demand for organs and the vulnerability of children. It's unlikely that a trafficker is going to take this risk and bring just one child into the UK. It is likely there was a group."
According to the World Health Organisation as many as 7,000 kidneys are illegally obtained by traffickers each year around the world.
The government's report a showed a total of 371 children were trafficked and exploited, with the majority of them used as slaves or sexually abused. They included 95 children from Vietnam, 67 from Nigeria and 25 from China. Others hailed from Romania and Bangladesh.
The figures also detail how 20 British girls have fallen victim to human traffickers following a series of cases of British girls being raped and exploited by Asian gangs.
David Hanson MP, Labour's shadow immigration minister, said that the government needed to increase the number of prosecutions, pointing to the last government report, which identified 946 potential victims of human trafficking, but "only eight convictions".
He said: "The government also needs to wake up to the fact that 60% of trafficked children simply go missing again in the UK after they've come to the attention of the authorities.
"It should be a source of shame."
Under new proposals the government now wants to give human traffickers previously convicted for serious sexual or violent offences a maximum life sentence.
The current maximum sentence for trafficking is 14 years.