Customs officers have seized more than 2.5 million contraband cigarettes from a lorry in Newhaven.
The vehicle was stopped in a routine inspection by officials as it left a ferry from Dieppe.
The smuggled cigarettes were hidden among a legitimate freight load in the truck, which was heading for the north of England.
Officers estimated the 2,504,800 Superkings would have evaded £411,000 of tax if sold on the black market.
Lewes MP Norman Baker described the news as a "double-edged sword".
He said: "I'm delighted that Customs officers have made a seizure but I assume it was based on intelligence rather than presence. Numbers of officers have fallen from 120 in 1989 to less than 15 today.
"The fact they have made a seizure shows perhaps intelligence is working, which is good news and they are treating the threat seriously. But officers have made one large seizure last year and now one this year, which shows smugglers have identified Newhaven as a soft touch.
"It's very important officers keep their presence there and send a message out to smugglers."
Customs spokeswoman Amanda Spencer said: "We are very pleased with this. It stopped a large consignment of cigarettes entering the black market."
A Portuguese man was questioned by police and released on bail.
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