Official data show that up to 13,000 people across the UK were victims of modern slavery in 2013, four times more than previously estimated.
The UK Home Office released the figures on Saturday following a study that aimed to calculate the number of previously unreported modern slavery victims.
The figure includes the women who have been forced into prostitution or sexually exploited for profit, “imprisoned” domestic staff, as well as workers on farms, factories and fishing boats.
The data was gathered from sources such as the British police, the UK Border Force, charities and the Gangmasters Licensing Authority, a British non-departmental public body.
According to the Home Office, many of the victims were taken to Britain by traffickers from more than 100 countries, with large numbers coming from the eastern European nations of Poland, Romania, Albania and the African country of Nigeria.
The Home Office said the figure is four times higher than the previous estimate of 2,744 victims in 2013 by Britain’s National Crime Agency (NCA), which had been presented in September.
Karen Bradley, the UK’s modern slavery and organized crime minister, had earlier described modern slavery as an appalling crime that has “no place in today’s society.”
The study by the Home Office comes as British lawmakers are debating legislation on the issue in parliament.