TEHRAN, Young Journalists Club (YJC) - Police, charities and other first responders referred 6,993 potential modern slavery cases to the government's National Referral Mechanism (NRM) last year, 36% more than in 2017, Britain's National Crime Agency (NCA) said in its annual report.
The NRM is a national scheme whereby victims are identified and can receive support ranging from healthcare and housing to legal aid.
Anti-slavery campaigners said it was unclear whether the figures represented an increase in modern slavery or resulted from a rise in awareness, but that the true scale of the problem was likely much larger.
"The true scale of modern slavery in the UK is simply unknown," Justine Currell, executive director of the anti-slavery charity Unseen, told the Thomson Reuters Foundation.
"But it is fair to say that the numbers we see through the government's National Referral Mechanism and Unseen's Modern Slavery Helpline are potentially the tip of the iceberg.
"Modern slavery is everyone's responsibility and we need to ensure that the public, frontline professionals, law enforcement agencies and businesses can spot the signs and know what to do if they think someone is in a situation of modern slavery."
Britain is home to at least 136,000 modern slaves, according to the Global Slavery Index by rights group Walk Free Foundation, with labor exploitation - from men working in car washes to children forced to carry drugs - the most common form.
British authorities have already launched several initiatives to enlist help from the public, including an app to report possible signs of modern slavery at car washes and guidance for hotel staff on what to look out for.
Jakub Sobik, spokesman for Anti-Slavery International, said authorities also needed to make it easier for victims to come forward.
"It's important that the British public is aware of modern slavery - what it is, what it entails, how to spot the signs and how to report it. But that's only a fraction of the response to slavery," he said. "No one will want to come forward if they're threatened with detention and deportation."
Britain is considered an international leader in the fight against slavery having passed the 2015 Modern Slavery Act to jail traffickers for life, better protect vulnerable people, and compel large businesses to address the threat of forced labor.
But some campaigners say too many survivors are being deported to nations where they risk becoming prey once more to traffickers.
The government has said it is committed to supporting victims of human trafficking and that those seeking asylum would not be returned to their country of origin if found to be at risk of persecution or serious harm.