More than 30 million smuggled cigarettes have been discovered in a shipment supposed to be full of wind turbines.
Border Force officers first discovered 8.5 million cigarettes, which are believed to be counterfeit, crammed inside a cargo container at Southampton Container Port on March 1.
Further investigation led them to another two 40ft containers full of the illegal imports, bringing the total seized to around 30.3 million cigarettes. The matter was then referred to HM Revenue and Customs (HMRC) for investigation.
John Cooper, HMRC assistant director criminal investigation, said: "The sheer scale of this haul would undoubtedly have seen criminal gangs selling the tobacco to retailers, clubs, car boot sales and eventually UK consumers. HMRC will continue to work with Border Force to crack down on tobacco fraud, which costs the UK Government around £1.8 billion a year."
The smugglers were trying to avoid paying over £8 million in taxes and duty and had described the containers' contents as "wind turbine parts" on import documents, the HMRC said.
The three cigarette-laden containers were loaded on to a cargo vessel in the Shenzhen area of China. The investigation is continuing and no arrests have been made, a spokesman added.
Samples of the seized cigarettes are being tested, but are believed to be counterfeits made to look like Lambert & Butler and Regal brands. They have now been shredded and burned at a power station to fuel the National Grid.
Andy Lumb, from the Border Force, said the containers were on their way to Glasgow, adding: "This was cigarette smuggling on an industrial scale so I am delighted that our officers have prevented this haul of contraband from reaching our streets.
"Tobacco smuggling is not victimless - it is effectively stealing from the public purse, at a time when the country can least afford it. I would urge anyone tempted by cheap cigarettes and tobacco to think again. The black market cheats honest traders and it is totally unregulated so buyers have no way of knowing what they are actually getting.
"The size of the detection should leave people in no doubt that tobacco smuggling is a serious organised crime, worth big money to the criminals involved. By stopping this shipment we have hit the smugglers where it hurts the most - in the pocket."