This report from Agence France Presse.

UK Police say cannabis production is a cash cow for organised crime, fuelling gang violence as groups compete for territory.

"We know that organised networks involved in cannabis production are also directly linked to an array of other serious criminality such as class A drug importation, modern slavery and wider violence and exploitation," said Steve Jupp, the National Police Chiefs' Council lead for serious organised crime.

"This operation not only successfully disrupted a significant amount of criminal activity, but the intelligence gathered will also help inform future law enforcement activity across the country."

Operation Mille saw searches and arrests carried out across England and Wales "at a scale and pace not seen before".

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"Nearly 200 000 cannabis plants with an estimated street value of between 115-130 million ($147 million - $166 million, 135 million - 152 million euros) were seized," police added in a statement.

Around 1 000 people were arrested and of those, "more than 450 were later charged".