There were 162 victims of modern slavery in South London in 2018, according to figures from the Government.
The numbers come as part of a campaign by the Government to alert workers in London to the signs of modern slavery that people display.
Croydon borough had the highest rate of modern slavery victims in the capital in 2018, with 45, which was nearly double the next highest – in Lambeth – which saw 23 victims.
North London had 258 victims in 2018, with Redbridge and Waltham Forest joint top boroughs with 21 victims each.
The Government has launched a campaign allowing people to spot the signs of modern slavery and labour exploitation and take action.
The campaign is asking workers in healthcare, banking and the employment systems to take a second look at the people around them for the tell-tale signs of exploitation.
A potential victim of labour exploitation may appear withdrawn, frightened or confused, be accompanied by someone who appears controlling or unwilling to leave them alone and may be posing as their relative or translator, or not be in possession of their own documents.
Frontline workers in finance, recruitment and healthcare are now being asked to spot the signs that others may not see.
These may include victims forced to pay cash wages into someone else’s bank account, sharing the same address as many others, and appearing vague when giving personal details.
Alex Aiken, executive director for government communications, said: “This modern slavery campaign will help to save victims from a life of exploitation.
“This is a example of how we can work with public services and the third and private sectors to save lives.”