Modern slavery prosecutions have increased by more than a quarter as authorities flag up record numbers of cases for possible criminal charges, new figures show.
The Crown Prosecution Service received 355 referrals frompolice and other agencies in 2017/18.
Charges were brought against 239 suspects - a 27 per cent rise compared with 2016/17.
The percentage charged, 67 per cent, has fallen from 83 per cent in 2014/15, although the overall caseload has gone up by more than 100 since then.
The figures relate to allegations of modern slavery or human trafficking that are referred for a charging decision, and prosecutions mounted under the Modern Slavery Act or other legislation.
Director of Public Prosecutions Alison Saunders said: "Modern slavery has a devastating, lasting impact on its victims.
"There is no place in our society for those who enslave others, whether for work, sexual or criminal exploitation or domestic servitude.
"We are working in partnership with police and other partners from the outset to make sure we can build robust cases and deliver justice for victims.
"These cases are growing in size and complexity - that's why we have given our prosecutors extensive extra training.
"Reducing the burden on victims and witnesses has been a key part of this training."
Out of 284 modern slavery-flagged prosecutions completed in the year to the end of March, 185 individuals were convicted, according to the CPS report.
The time taken on average from an alleged offence to completion of a case has doubled compared to 2015, now standing at nearly three years.
This "reflects the challenges in investigating and prosecuting such cases, with greater complexities, multiple defendants and multiple victims", the paper said.
Modern slavery encompasses a broad range of offending including exploitation, forced labour, domestic servitude and human trafficking.
An official estimate previously indicated there are up to 13,000 potential victims in the UK, but experts have said the number is now significantly higher.
Minister for crime, safeguarding and vulnerability Victoria Atkins said: "This is a clear and stark warning to perpetrators of modern slavery and human trafficking - there is no hiding place for those who seek to exploit and harm others.
"These figures reflect years of work by Government, prosecutors and law enforcement.
"However, we want to go further as this crime evolves and have recently announced an independent review of our laws to explore what more we can do to tackle this awful crime, both in the UK and abroad."