Lucy Viner-Mood (right) and Lois Gibson (left) were described as "feral" after luring Georgia Fenn to their flat before subjecting her to a ferocious 18-hour assault. (AFP/Handout)

Two British women have been sentenced to jail Friday after admitting they locked another woman in their apartment and beat her for 18 hours.

Lucy Viner-Mood, 22, and Lois Gibson, 18, attacked Georgia Fenn, 19, on March 28 after hearing that she slept with Viner-Mood's ex-boyfriend. Britain's Sky News reports that during those 18 hours Fenn was trapped, she was burned with cigarettes, doused in boiling water, suffered two black eyes, a broken nose and was beaten unconscious. Fenn was kicked out of the apartment the next day covered in blood and wearing only a robe.

Viner-Mood was sentenced to five years in jail for false imprisonment and assault causing actual bodily harm while Gibson is to spend three years at a young offender institution for the same offences.

"It's been a really dreadful time and I have been really badly affected," said Gibson in court Friday. "I'm not sure I will ever be right."

The judge called the attack "evil" and Det. Const. Adrian Grew said, "The behavior of Lucy Viner-Mood and Lois Gibson can only be described as feral. The level of violence shown during their sadistic attack was made all the more shocking by the length of time it went on for."