POLICE in Greater Manchester raided and closed down 351 cannabis farms last year.

The astonishing figures also showed 61 of the drug factories were controlled by either Chinese or Vietnamese defendants.

Officers found the farms - the equivalent to almost one a day - during an operation codenamed Dragonfly, set up to target sites being used for large scale cannabis production.

The figures were disclosed in a short statement from a GMP detective handed to a judge at Manchester Crown Court before he sentenced two `gardeners' arrested after another cannabis factory was found in Burnage.

Mei Yu, 38, and Shi Yao, 22, were due to be paid between £20 and £30 a week to `water' the 319 plants being grown at the house in Glendale Avenue.

But, Judge Robert Atherton was told, they had only been looking after the plants for less than two weeks before they were arrested at the house.

The men, both illegal immigrants from China, were jailed for 12 months after they admitted producing the drug. Judge Atherton said: "Unfortunately, and my impression is reinforced from the information I have been given, the cultivation of cannabis is a common offence.

"Such offences are serious because the use of cannabis is serious. There can be no doubt that cannabis properties are detrimental to the health of users."

Judge Atherton said he accepted Yu and Yao were `to an extent' victims of others who set up cannabis farms and use illegal immigrants to run them.

But he added: "You are mature men who knew you were taking part in criminal activities to the detriment of the citizens of the United Kingdom."

Christopher Beckwith, prosecuting, said the plants were found after police went to the house which had been rented by `a Chinese person' who, it was accepted, was neither of the defendants.