The bust is part of an operation against a Spanish-Chinese network dedicated to growing and exporting narcotics on a large scale, in which 41 arrests have been made and 30,351 plants seized to date, police said.
The organization's plantations were distributed across different provinces in Spain in order to make it more difficult to detect them and assure continued production in the case of one being located. The raids in Barcelona and Girona marked the closure of the final production locations.
Facilities were housed in a variety of buildings including family homes, which also doubled up as safe houses for members of the network, who changed their address every six months.
"The detainees had perfected their criminal activity to such a degree that they even lined the rooms where they cultivated the marijuana with thermal insulating material, which gave the room a complete seal, preventing them from emitting odours as well as the detection of heat sources," the Policia Nacional said on its website.
A total of 2,477 plants, 34 kilos of seeds, 1,180 grams of buds, a vehicle and 32,300 euros in cash were seized in the Barcelona and Girona raids.
"With the eight arrests made the organization is considered to be dismantled," the police concluded.