Heroin with a street value of more than £120 million has been discovered hidden among towels and dressing gowns on board a container ship.
The National Crime Agency (NCA) said the haul, weighing nearly 1.3 tonnes, is the largest ever seizure of the Class A drug in the UK.
The heroin was recovered from a container on board the MV Gibraltar after the vessel docked at the port of Felixstowe on August 30.
It took officers almost six hours to remove the haul, which the NCA said had a street value of more than £120 million and a wholesale value of £27 million to organised criminals.
Video footage of the seizure shows the drugs were stored in packets labelled as protein powder, which were inside boxes filled with towels and dressing gowns.
The NCA said intelligence had ascertained the drugs would be on the MV Gibraltar as it docked in the UK en-route to Antwerp.
The vessel was searched by Border Force and NCA officers as it arrived at Felixstowe, and 1,297kg of heroin was found inside.
After the drugs were removed, officers returned the container to the ship, which continued to Antwerp and docked in the Belgian port city on September 1.
The container was kept under surveillance by Dutch and Belgian law enforcement agencies as it was driven by lorry to a warehouse in Rotterdam, the Netherlands.
On arrival, officers swooped in and arrested four people as they unloaded the container.
The latest seizure comes after officers discovered 398kg of heroin on a vessel at Felixstowe port on August 2.
NCA deputy director, investigations, Matt Horne, said: “This is a record heroin seizure in the UK and one of the largest ever in Europe.
“The size of this and other recent shipments demonstrate the scale of the threat we face.
“We can be certain that some of these drugs would eventually have been sold in the UK, fuelling high levels of violence and exploitation including what we see in county lines offending nationwide.”
Jenny Sharp, Border Force assistant director at Felixstowe, said: “This is a huge seizure, there is no other word for it given the quantities involved, which has kept dangerous drugs off the streets of the UK and mainland Europe.
“The smugglers had hidden the drugs within a cover load of towels, stitching the 1kg blocks of heroin inside some of the towels.
“In total it took my officers nearly six hours, working in the early hours of Saturday morning, to remove the drugs.”