Councils have warned of a rise in the number of potential modern slavery victims identified as they called on the public to act as the “first line of defence” in efforts to tackle the scourge.

Town halls highlighted official figures showing a jump in cases flagged up to authorities last year.

From July to September, 1,322 people were referred to the National Referral Mechanism, a framework established to identify potential victims.

This was a 10% increase on the previous three months, and a rise of nearly half (47%) compared with July-September 2016.

The Local Government Association (LGA), which represents councils in England and Wales, is urging residents to familiarise themselves with a number of warning signs.

These include large groups being transported to properties in vans, people seeming to have been deprived of food, water, medical care or sleep, or who look as if they are being instructed or coached by somebody else.

Simon Blackburn, chairman of the LGA’s safer and stronger communities board, said: “Being forced into domestic servitude, being trafficked for work, or subject to exploitation is a horrendous fate, and one most of us can’t even imagine – but the sad truth is that there is a good chance that modern slavery is taking place in the towns, cities and villages where we live.

“Modern slavery can be hidden, often in plain sight; on our high streets, in local businesses and even in suburban streets.

“Our residents may be unwittingly using victims of modern slavery to wash their cars, paint their nails or lay their drives, unaware of the hell they are living through.

“Members of the public are our first line of defence when it comes to tackling this scourge, and we urge all our residents to be aware of the tell-tale warning signs of modern slavery, and report any concerns to police or their local authority.”

Modern slavery encompasses a range of criminality including servitude, forced labour and human trafficking.

An official estimate previously suggested there are up to 13,000 potential victims in the UK, although the anti-slavery commissioner has described the figure as “far too modest”.

Kevin Hyland, the commissioner, said: “The important role that the public and local council staff can play in identifying and disrupting modern slavery crimes should not be underestimated.”