Thousands of British children are being exploited and groomed by drug gangs in increasingly violent ways, a new report reveals.

To expand their drug networks while avoiding detection, gangs are preying on children as young as 12 and sending them away from their homes to sell Class A drugs. Authorities have also reported a rise in violence linked to the gangs and the young people they have control over.

In an interview with ITV News, a former gang leader revealed how he would target vulnerable young children.

"I groomed and I taught my gang members how to groom other kids," Matthew Norford said.

Norford, who is reformed was introduced to gang life by his older brother and his friends when he was just 13 years old. He was candid about how easily he got vulnerable children to trust him and do his gang's bidding.

"You look at the young kid who have no trainers, no parents, who's always on the street, not good at school, wants to be accepted and is just happy to be around you," he said. Norford said he would buy the children expensive trainers and tracksuits and seduce them with the "glamorous" lifestyle of his gang.

One his targets felt "part of the family," Norford would send the children miles away from their homes to sell crack cocaine and heroin. "I didn't care, you can't care - it's all about making money," he said.

Norford was making £2,000 a day selling heroin and crack cocaine in Manchester, but wanted to expand his operation. He decided to send groomed young drug mules into Birmingham and Preston to move beyond a saturated Manchester market.

"Police ain't looking at some who's 14, 15 with a school bag on and you're not going to get caught so you can sit back and reap the rewards without the pain."

Police are now concerned that the practice of grooming young children to sell drugs, known as county lines, is spreading and that gangs are using increasingly extreme violence to control them.

Like Norford, gangs will send the youngsters with Class A drugs to a new territory, give them a movie phone and put them up in the homes of local addicts. The children are then forced to hand over drugs to customers 24 hours a day.

A former drug mule described the terrifying time he was forced to deliver cocaine and heroin to clients in London. "I was scared, they were older than me and I knew their reputation so I knew I couldn't do anything about it," "Andre" said.

According to ITV News, of 45 police forces across the UK, 32 have reported significant increases in violent crime linked to country lines. Some forces have noted an increase in the use of knives, bats, hammers and boiling water.

"Extreme violence, humiliation and torture are common place, with dealers deliberately creating a culture of fear, intimidation and human misery in order to control their victims is commonplace," a force said.

Andre warned that gangster do not care about young people's lives and that they see them as "easily replaceable".

"They didn't care what happened to me. False loyalty exists and a lot of young people think they are looking out at them but really if you get arrested or killed, they'll just get someone else," he said.

"Those lies: we'll help you look after mummy, feed you, buy you trainers but they'll drop you at the drop of the hat. It's like modern day slavery - 100%."