The extent of modern slavery in the UK is likely to be higher than previously estimated with up to 13,000 victims believed to be in the country, according to Home Office findings.
This is the first time the government has mentioned an estimated figure of modern slavery in Britain. The government says the victims hail from more than 100 countries.
According to the 2013 figures, the majority of the victims are from Albania, Nigeria, Vietnam and Romania while some of them are British-born, reports the BBC.
Modern slavery victims include females forced into prostitution as well as locked up domestic workers and others.
The UK Home Office says it has several measures in place to tackle the problem.
"The time has come for concerted, co-ordinated action. Working with a wide-range of partners, we must step up the fight against modern slavery in this country, and internationally, to put an end to the misery suffered by innocent people around the world," said Home Secretary Theresa May.
The Home Office says its "tentative conclusions" on the number of slavery victims are much higher than previously estimated by the National Crime Agency's Human Trafficking Centre, which put the figure at 2,744 last year.
It was earlier reported that some diplomats to the UK are allegedly abusing their power by trafficking domestic workers under inhumane conditions in what could be described as modern slavery.