A couple from the Democratic Republic of Congo were convicted of torturing and murdering teenager Kirsty Bamu on Thursday on suspicion of being a witch, indicating the rising trend of witchcraft in Britain.

The Metropolitan Police yesterday issued a warning saying the killing is not the first in Britain to involve claims of witchcraft, as they have investigated 83 “faith-based” child abuse cases in the past 10 years.

UK social workers were told by children’s charities and campaigners to look for signs of witchcraft in cases of child abuse, as police believe witchcraft is still an “under-reported, hidden crime”.

15-year-old Kristy Bamu was tortured and drowned in a bath on Christmas Day 2010 at a flat in Newham, east London by his sister Magalie and her boyfriend Eric Bikubi. The couple attacked him with knives, sticks, metal bars, a hammer and chisel after accusing him of witchcraft.

Kristy and his siblings were visiting Eric Bikubi and Magalie Bamu for Christmas from Paris in 2010, where Bikubi accused the boy and two of his siblings of witchcraft. All three were beaten and but Kristy became the focus of Bikubi’s attention.

The problem in Britain is believed to be fuelled in back street churches by pastors. Det. Supt. Terry Sharpe, the Metropolitan Police’s lead on Project Violet, a team set up to tackle religious-based child abuse, said “The intelligence from the community is that it’s far more prevalent than the reports we are getting.”

The NSPCC said, “We must not be afraid to challenge these communities to out the wrongdoers within them. Sadly, this deeply disturbing case is not a one-off incident.”