HUNDREDS of cannabis farms like the ones set up in a quiet Bolton street are being discovered across England, a study has found.

Police discovered about 400 mature and young plants in two homes in Queen's Avenue, Bromley Cross, last week.

But the charity DrugScope said three similar factories were being raided every day by police in Britain as the amount of cannabis grown in the country continues to soar.

A £20,000 farm was found at a house in Blackburn on Friday and three men from admitted growing the Class-C drug in August last year after plants worth £130,000 were found in a Salford flat.

It is now thought that 60 per cent of cannabis smoked in Britain is now home-grown, a six-fold rise from a decade ago.

The boom in British-grown cannabis is said to be driven by Vietnamese gangs who have set up farms to profit from the drug.

In Bolton, police are hunting two men, said to be of Oriental appearance, who were seen fleeing the house in Bromley Cross when the farm was discovered on March 6.

The sophisticated operation in Bolton included lights, fans and a complicated watering system to nurture the plants while the houses were empty.

An electrical engineer discovered the farm after being called to investigate a power failure at a neighbouring house.

Sgt Dave Kehoe, of Bolton police's drugs unit, said: "Although we tend to target those who deal in heroin and crack cocaine at street level, we are aware that there are people who are seeking to make huge profits very quickly from growing cannabis.

"Very often these farms are set up with the proceeds of crime and linked to much more serious criminal activity.

"Although this hasn't presented itself as a huge problem in Bolton, the discovery of this farm makes it clear it is something we have to take seriously and our inquiries are ongoing."