What could be Somerset's biggest drug bust of the century has been made in the most unexpected of places.

Police raided a sleepy farm in the Cheddar Valley early Wednesday morning – uncovering a high-tech drugs factory stuffed with enough pungent-smelling cannabis to flood the rural area for miles around.

The copious amounts of the Class B drug have not been weighed, but its street value is estimated at half-a-million pounds.

The raid near Tarnock – a quiet village on the A38 between Rooksbridge and Badgworth – is believed to have busted open an unsuspected major drugs operation hiding in the countryside.

One man in his 30s has been arrested on suspicion of producing cannabis.

The drugs pinch came after an anonymous tip-off from Crimestoppers.

The haul is the biggest of the century in the Somerset West police district – and possibly the largest in the entire county.

Three industrial units – each dedicated to cultivating hundreds of plants of cannabis at various stages in the drug cycle – took the best part of two days to dismantle. One unit was the size of a school sports hall.

Three skips were needed to cart away the drugs paraphernalia and stacks of bundled-up cannabis is stinking out the lock-up at Cheddar police station.

Sergeant Elaine Linham has been in the job two months at the station when the sting was made.

She said: "It is a classic example of the public aiding the police. It shows how serious we take information from Crimestoppers and because of that anonymous person the drugs are of the streets and not being sold to our children.

"We are overjoyed with completely destroying this drug-producing business. It is a very happy day."

An investigation to find out what links the premises has to the criminal underworld and where the drugs were destined to go is being led by Cheddar beat officers, the Criminal Investigation Department and a financial investigation team.

Avon and Somerset Police spent two weeks scoping out the innocuous looking buildings with infrared-equipped helicopters and scrutinising electricity usage before pouncing on the premises with officers from Cheddar, Taunton and police dogs.

They found a professional hydroponics set-up of lighting rigs dedicated to growing drying and harvesting the cannabis crops. Even packaging equipment was found.

It is thought the well-established operation, which had 260 growing plants and 470 already harvested, had been up and running at least a year.

Anyone who has information about the operation can contact Crimestoppers or Cheddar Police Station on the above web links.