IT’S seen as a ‘soft’ drug, without the links to underworld gangs and brutal violence that cocaine and heroin have.

But a Sun Online investigation can reveal that behind Britain’s cannabis trade lies a dark and shocking reality, in which around 3,000 slave children are cultivating crops in dire conditions.

And most of those kids are Vietnamese teenage boys who have been ripped from their families by traffickers, who smuggle them into the UK and force them to work in secret drug dens in houses all over Britain.

Once here, many endure horrific conditions, beatings and sexual abuse at the hands of gang masters.

Children as young as 11 are forced to survive on scraps as they tend cannabis farms, and one man was even reduced to eating dog food to stay alive while he grew weed for gangs.

Their suffering has led anti-slavery campaigners to coin the phrase ‘blood cannabis’, to reflect the true horror behind some of Britain’s £2.6bn-a-year illegal weed market, which sees an estimated 255 tonnes of weed smoked annually in the UK.

The National Crime Agency says 96 per cent of trafficking victims forced to grow weed in Britain are Vietnamese, and 81 per cent of those are children.

Many of them are dangerously smuggled into the UK in lorries — the death of 39 Vietnamese people, including 10 teenagers, in Essex in October highlighted the lethal peril of such journeys.

Police are too busy to focus on weed farms

Giant cannabis farms have been uncovered all over the UK — including in town centre bingo halls and even a disused police station — but thousands of smaller operations are being run all over the country.

In London alone between 2016 and 2018, police found 314 illegal cannabis farms, but the true scale of cannabis growing in the UK will never be known as they’re illegally run in residential properties and shop backrooms.

For users, an eighth of an ounce (3.5g) of cannabis costs around £20, and a full ounce (28.3g) will set you back around £180 — which is cheaper than prices of legalised cannabis in the USA.

Horrifyingly, government figures released last week show raids on cannabis farms have plummeted in the last seven years as police forces focus resources elsewhere.

And millions of Brit users have helped the trade thrive — around 30 per cent of the UK population aged between 16 and 64 admit to having tried cannabis, which is roughly 10 million people.

Fingers cut off children

The victims are children like Le, orphaned at just 11 years old.

He was left saddled with loan shark debt from paying his dying mum’s hospital bills in his Vietnamese homeland.

He was taken in by a convent – but was kidnapped by money lenders who demanded church elders hand over Le’s family land to settle the loan.

Their ultimatum came with a grisly threat – a package containing Le’s severed finger.

Although the church tried to help Le, he was put to work by his captors in a warehouse, where he was kept in chains and fed scraps.

After being sold to a gang in China, he was sent on a perilous lorry journey across Europe to the UK.

Forced to work on an illegal cannabis farm he grew so hungry he tried to eat the plants.

When police raided the cannabis farm, he was rescued and taken into local authority care.

But after meeting a man in a shopping centre who spoke Vietnamese, he was enslaved again and put to work in a warehouse.

Phil Brewer, former head of the Met’s Anti-Trafficking Unit, says that’s because cannabis slaves are coached to mistrust the authorities.

“They don’t speak the language and have nowhere to go,” he explained. “The fear factor takes over and they gravitate back to what they know, back to exploitation.”

Le eventually managed to escape his new captors and was given refuge in a safe house by the Salvation Army. But they say he lived in fear of deportation or of being found by gang masters.

One day, he left the safe house and never returned. Nobody knows what happened to him.

Le’s agonising story is far from unique.

While some, like Le, are kidnapped from orphanages or the streets into slavery, others voluntarily leave behind their families in rural Vietnam in search of a brighter future.

They are enticed by traffickers with false promises of exciting job offers or student exchanges.

But instead they spend years in servitude, passed from grow-house to grow-house, under the thumb of brutal organised crooks, as they work off the cost of their passage to Britain.

Police raids have revealed the nightmare existence endured by these slaves, whose work exposes them to toxic chemicals, fire risks, and violence from rival drug gangs.

Survived by eating dog food

In October, police rescued three Vietnamese children found living in squalor in an industrial unit in Rochdale.

In April 2015, a 32-year-old Vietnamese man was found surviving on tins of dog food at a house in Northern Ireland, where cops recovered over 500 weed plants.

And in 2017, four young Vietnamese workers were discovered sleeping on mattresses and locked in a subterranean nuclear bunker while they tended 4,000 plants in an operation worth £2m a year.

Brewer says: “Cannabis is seen as a bit of a soft drug, unrelated to violence and sold through traditional drug dealing methods. I don’t think people always make the link to the violence and control that goes with it.”

Efforts to take down the kingpins behind the trade have had piecemeal success.

In September, 20 gang members were jailed after a joint sting by the NCA and three police forces in south Wales.

The investigation uncovered a network of 45 cannabis farms and storage units as far away as Coventry, thought to have netted the gang £25m.

Cops losing fight against gangs

But despite the success of some high-profile operations, police only busted 8,600 cannabis farms in 2018-19 – a thousand more than the previous year but still just over half the 16,590 raided in 2011-12.

And Volteface, a non-profit group campaigning for cannabis legalisation, says Ministry of Justice data obtained under a freedom of information request shows prosecutions for growing weed fell 63 per cent in the five years to 2018.

It comes down to police budgets and priorities.

Volteface director of policy Liz McCulloch, said: “Police are withdrawing from policing cannabis markets.

“Their budgets are stretched and it’s not a priority anymore.

“Growers are probably a bit more confident there’s a good chance their activities aren’t going to be found out.”

Tony Saggers, former head of the NCA’s Drugs Threat and Intelligence added: “We seize what we look for, and we look for what we prioritise.

“Considering all the pressures on policing, not least another drug generated threat in County Lines – it doesn’t surprise me that less focus has been on cannabis, this does not mean it is not still being taken seriously”

Mimi Vu, a world expert on the trafficking of Vietnamese children and young people, hopes the container tomb tragedy in Essex will serve as a wake-up call for Vietnam’s youth to seek their fortune in their own booming economy, instead of gambling their lives on a deadly lorry journey to the UK.

“They grow up believing their best bet is to go overseas,” she says. “But what happened in Essex has brought everything into the open, and shown that the dangers are real.

“There’s no way now that anyone can say we’re making up stories to scare them off.”

But even if fewer Vietnamese do decide to make that perilous crossing, police intelligence reveals there will still be a plentiful supply of trafficked slaves to help grow weed.

There is growing evidence that ruthlessly efficient Albanian gangs are now moving into cannabis.

And Home Office data suggests the number of trafficked Albanians exploited in the UK for labour – which includes cannabis farms – is on course to double this year.

Tony Saggers, former head of the NCA’s Drugs Threat and Intelligence says, cannabis users should give more thought to the human cost of lighting up a spliff.

“Leisure users blame prohibitionists and the law for preventing them the freedom of choice to use cannabis,” he says.

“There’s a selfish inclination to do what they want instead of thinking of the wider consequences.”

*Le is a false name. His whereabouts are still unknown.