London drug dealers are selling cannabis to primary school children, an investigation has revealed.

The leader of a drugs gang operating in south London said he employs more than 30 people to run three factories supplying drugs in the capital, and even claimed he exports a strain of cannabis called 'English Cheese' to the Netherlands, Germany and Austria.

He was filmed by Sky News under condition of anonymity saying Britain's cannabis trade is "the biggest it has ever been", adding that his gang sells drugs to people from all walks of life.

"You've got doctors, police, solicitors, teachers, bus drivers - everyone does it.... young kids, school kids, even primary school kids," he told the network.

"We have a type of weed over here called 'English cheese'. It was created over here - in Amsterdam they don't have that so they try to create that but they just can't because it is what we make and that's what they want."

Although he said he did not personally sell drugs to children still at primary school - who are under the age of 11 - the gang boss said the dealers who work for him do.

And he blamed drug use among young children on wider society and the glamorisation of cannabis by celebrities such as Miley Cyrus, who was filmed apparently lighting a joint on stage at an awards show last year.

He said: "I blame it on the TV, the media, rap, YouTube, like Miley Cyrus on TV it is a common thing - they see it as the cool thing to do.

"Instead of binge-drinking they'll go and have a smoke."

Calling for laws controlling the Class B drug to be relaxed, he added: "It should be legal so we don't have to hide what we are doing.

"If you look at LA and California and how they legalised it for medical reasons and stuff and how the crime rate actually drops. They legalised and it's a calmer place out there."

The Metropolitan Police's gangs and organised crime division leader Commander Steve Rodhouse admitted the cannabis trade remains "a real problem on our streets".

He told Sky: "We do thousands and thousands of search warrants every year in London. We arrest and charge hundreds of people for this crime."

And Crime Prevention Minister Norman Baker said: "We are determined to bring the criminal gangs who trade in cannabis to justice.

"I am also leading a study of drugs policy in other countries, which will build on the commitment in the drug strategy to look at what we can learn from the approach taken abroad."