Large numbers of children are believed to be working as slaves on illegal cannabis farms in the United Kingdom, experts warned, according to Thomson Reuters Foundation.
Since 2016, police have found 314 illegal cannabis farms, according to Scotland Yard data obtained by the London Evening Standard.
Experts believe there are potentially thousands of children from countries, such as Vietnam, who are being trafficked and exploited into modern slavery in the United Kingdom.
"The high number of cannabis farms across London and trafficking of Vietnamese children to work in them is extremely worrying," Jakub Sobik, a spokesman for Anti-Slavery International, told Thomson Reuters Foundation.
"Potentially thousands of children and young people are being trafficked from Vietnam and exploited by ruthless criminal gangs," he added.
Authorities have discovered cannabis farms or factories in every borough of London, according to The Standard. Most are located in residential areas and the highest concentration was in south London.
Many trafficked children are allegedly treated as criminals by authorities, according to Catherine Baker, a policy officer at Every Child Protected Against Trafficking UK, an organization that is working to end child exploitation.
"It is vital that these children are seen by police as victims first and foremost, and given proper support, as too often they are treated as criminals instead," Baker told Thomson Reuters Foundation.
What do investigators say?
Detective Superintendent Lee Hill who works in the Croydon, Sutton, and Bromley boroughs, told The Standard that the problem is serious and it's a "big concern" for police.
Hill said he often finds children who've been forced into slavery at the farms and it's “destroying young people’s lives.”
In Croydon alone, 30 illegal cannabis farms have been found.
Lee said several factors contribute to the number of farms discovered in Croydon, including a large population and violent gang activity.
“I think we can make links to gang activity. Some of the recoveries are within gang territory areas. A lot of it does comes down to organised criminality,” Lee said. “There’s a link between violence and drugs, we do recognise that drugs underpin some of that.”
What about the UK's fight against modern slavery?
In 2015, the government passed the Modern Slavery Act. The legislation called for more protections for vulnerable people and for life sentences for those found guilty of human trafficking.
Earlier this year, the British government received backlash when it refused to grant asylum to a Vietnamese orphan who was trafficked into Britain and forced into slavery at an illegal cannabis farm.
"These vulnerable children are exploited in extremely dangerous conditions, with little or no pay and may be physically and psychologically abused by their traffickers," Baker told Thomson Reuters Foundation.
Last year, more than 2,000 exploitation victims were referred to British authorities, up by 66 percent over the previous year, according to the report.
Britain is home to at least 136,000 modern-day slaves, according to the Walk Free Foundation's 2018 Global Slavery Index.