POLICE have seized cannabis plants with a street value estimated at more than £1.5m in raids on four properties.

Up to 40 detectives, supported by uniformed colleagues, raided a converted barn in Lanchester, a three-bedroomed semi- detached house in Ushaw Moor, a three-storey home in Sacriston and a terraced house in Bowburn, all County Durham, at about 9pm on Thursday.

Twelve men in their late teens and early 20s were arrested on suspicion of being involved in the cultivation or possession and supply of cannabis. The men, one from eastern Europe and the remainder believed to be from Vietnam or of east Asian origin, were taken to police stations in Peterlee, Durham City and Bishop Auckland, where they continued to be held for questioning last night.

Acting Detective Superintendent Ken Donnelly said an estimated 1,000 cannabis plants were being grown in Lanchester and between 700 and 800 at the Bowburn and Sacriston properties.

Cannabis and a large amount of money, believed to be thousands of pounds, were identified by officers during the raids. A number of vehicles were also seized.

Each of the four properties was sealed after the raids, and was guarded overnight by uniformed officers.

Acting Det Supt Donnelly said: "The raids went well. From the perspective of public safety, there was no violent confrontation and we took possession of a really substantial amount of cannabis.

"This is certainly a problem police are having to deal with more often.

"The negative thing is that there is a market there that is being fed.

"People need to understand that when they buy into that market, they are not only buying the drug, but are buying into organised crime."

Acting Det Supt Donnelly said: "The setting-up of drug farms is not confined to deprived areas. There is enough money in this trade for them to buy into residential areas."

The raids come several months after eight people, all of Vietnamese origin, were jailed after large drugs farms were found in three houses in County Durham.

Last week, four of the men and one woman were ordered to hand over more than £414,000 of realisable assets at a confiscation hearing at Newcastle Crown Court.

Acting Det Supt Donnelly said police were looking into previous investigations to determine if there were links with the raids.