More than 130,000 Ecstasy tablets with an estimated street value of £1.78 million have been seized at Newhaven port.
The haul was made on Thursday morning after customs officers searched a British-registered lorry that had just crossed from Dieppe in France.
A wooden crate containing 44.5kg of the Class A drug was found in the lorry, which was carrying a mixed load of goods from Germany.
Both drivers in the lorry, a 52-year-old man from Barnsley and a 38-year-old man from Stockport, were arrested and interviewed but later released on bail pending further inquiries.
A spokesman said: "We are delighted with this seizure. With an estimated street value of £1,780,000 it is the largest seizure of Class A drugs we have ever had at Newhaven.
"We believe the drugs may have been destined for the north west of England. We are pleased to have stopped such a large quantity of drugs hitting the streets."
He added that the haul was one of the biggest single seizures of the drug by customs this year.
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