Cannabis plants worth an estimated £600,000 have been seized from a warehouse in Friday Bridge.
Around 1,000 plants were discovered at the site in March Road yesterday afternoon, after three men were seen running away from the area.
Detectives believe the farm, which is the second major cannabis factory to be found in Fenland in as many weeks, is linked to organised crime.
Det Insp David Murphy of Cambridgeshire Police, said: “It’s huge. It’s good disruption for us. This will hurt them, which we’re pleased about.”
He revealed the operation had been discovered by officers from a safeguarding team based in Wisbech when they spotted vehicles known to them in the area.
He said: “It’s really good policing. As they’ve approached the site, three lads have run off at speed, literally vaulted over the fence and made good their escape.”
He said the men were thought to be foreign nationals and it was possible they were there as a result of potential exploitation.
He said: “We’re possibly protecting them from further harm. It’s the people behind them we’re after.”
Officers are expected to remain at the site for much of the day to dismantle the set-up. Power supplies had also been diverted into the warehouse in a manner the police described as “incredibly dangerous.”
Forensic tests are also being carried out, though the results of those are not expected to be known for several days. No arrests have so far been made.
The discovery was made just 10 days after 200 plants, with an estimated street value of £100,000, were found at a house in Princes Road, Wisbech.
A 21-year-old man remains on bail in connection with that case.
The latest find is not currently being linked to the Wisbech case, but Det Insp Murphy said officers were keeping an “open mind.”
And he vowed that the force would continue to crack down on the trade.
He said: “This just reaffirms our zero tolerance approach to drugs. Cannabis is far stronger now than it was 15 or 20 years ago and we know the effects it does have on people’s health.”