LONDON - Eleven people were sentenced on Thursday for trafficking sex workers from Hungary to Britain, in what the Crown Prosecution Service (CPS) said was one of the largest sex trafficking cases prosecuted in London.

At least 250 sex workers were trafficked for the purposes of sexual exploitation and the case involved 50 brothels in London and Peterborough, said the CPS.

"While in many cases the women were voluntarily working in prostitution, they were trafficked here to be exploited and controlled, the women having to give up to half of their earnings for the privilege of working in a house or brothel run by the defendants," prosecutor Baljit Ubhey said in a statement.

"I hope this case demonstrates our commitment to working with partners both in the UK and overseas in tackling organised crime involving trafficking and sexual exploitation."

The group of men and women were aged between 28 and 53 years old and received prison sentences ranging from 20 months to 14 years on counts of conspiracy to traffick people to the United Kingdom and conspiracy to control prostitution, the CPS said. One man was also convicted on two counts of rape.

Up to 13,000 victims of modern slavery in Britain are forced to work in factories and farms, sold for sex in brothels or kept in domestic servitude, among other forms of slavery, according to the Home Office (interior ministry). Most come from Albania, Nigeria, Vietnam and Romania.

The global industry is estimated to generate $150 billion a year in profits for those who exploit modern-day slaves.

Britain passed the Modern Slavery Bill in March to crack down on traffickers, clean up supply chains and protect people feared at risk of being enslaved.