The report released Friday said the girl is the first child known to have been a target of an illegal organ harvesting operation in Britain, The Daily Telegraph reported. But child advocacy groups warned that the unidentified girl is unlikely to be the only victim.
"Traffickers are exploiting the demand for organs and the vulnerability of children," said Bharti Patel of ECPAT U.K. "It's unlikely that a trafficker is going to take this risk and bring just one child into the U.K. It is likely there was a group."
The World Health Organization estimates 7,000 kidneys are illegally harvested every year globally. They are the most popular organs involved in illegal trafficking because, unlike hearts or lungs, they can be removed with comparatively little risk to the donor.
The report said that a total of 371 children targeted by human traffickers were discovered in the past year in Britain. Most were used for slave labor or as sex slaves.
In one particularly horrifying case, an elderly man was convicted this past week in Manchester of repeatedly raping a deaf girl he and his wife brought from Pakistan. Investigators said the couple exploited the girl in several ways, using her as a domestic servant and collecting thousands of dollars every year in benefits for her -- which they then spent on themselves.
Notable deaths of 2014 [PHOTOS]