Drugs officers have seized £120 million of heroin in what is thought to be the largest raid of the class A drug carried out by the National Crime Agency (NCA).
The NCA said that the haul was discovered underneath dressing gowns and towels on board a container ship during the seizure on August 30.
Around 1.3 tonnes of heroin was found on board the MV Gibraltar when officials from the agency docked the vessel on the port of Felixstowe, near Ipswich.
It took officers almost six hours to remove the haul, which the NCA said had a street value of £120 million and a wholesale value of £27 million to organised criminals.
Intelligence led the NCA to the huge amount of drugs on board the container ship as it was en-route to Antwerp, Belgium.
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."
