BBC South East uncovers black market in banned 'legal highs'
Banned "legal highs" are being sold illegally by drug dealers who are producing new and more potent substances, BBC South East has found.
An undercover investigation has discovered an underground market across the South East.
Drug addicts are buying potentially lethal substances from street dealers and the dark web after so-called "head shops" were shut down.
The Home Office said its drug strategy was tackling the illicit trade.
Psychoactive substances designed to mimic the effects of cannabis and other illegal drugs used to be sold in "head shops" but were officially banned in 2016.
More than two years on, BBC South East has discovered they are still being widely bought and sold - in prisons, by street dealers and on the dark web.
In secret filming, one Brighton dealer sold a reporter two bags of Spice at £10 a bag.
Tests confirmed the sample contained a synthetic cannabinoid.
Now substances are sold on the street, they no longer come in branded packets - so users are often less aware of the substances they are buying.
One homeless Spice addict, called Jamie, believes the substance has become more potent since the ban.
He said: "We smoked it and it's just like really really intense, like out of control."
Another addict, Ben, said: "I just took three puffs out of one, and my arms were out laying on the grass, and I was out cold."
Recovering addict Christopher Mark said: "I got sick, I thought I was going to die."
A Home Office report has shown since legal highs were banned, the use of Spice among prisoners and homeless people has increased.
Criminologist Dr Caroline Chatwin, from the University of Kent, said: "When we prohibit things in general it pushes producers to make stronger versions of those drugs because they are more profitable."
A Home Office spokesman said: "Synthetic cannabinoids, such as those supplied under the brand name Spice, can have a devastating impact on individuals, families and communities.
"Since the Psychoactive Substances Act was introduced there has been a significant fall in the use of new psychoactive substances.
"Our Drug Strategy brings together police, health, community and global partners to tackle the illicit drug trade, protect the most vulnerable and help those with a drug dependency to recover and turn their lives around."