£120 million of Class A drugs found in Felixstowe
Four people have since been arrested in connection with the haul.
An operational led by the National Crime Agency (NCA) and supported by Border Force has resulted in almost 1.2 tonnes of heroin and morphine derivatives from potentially hitting UK streets.
The Class A drugs were found in bags of rice in a container on the Sembawang ship on Saturday 12th September.
The NCA had intelligence the drugs would be there as it docked at Felixstowe, on it's way to Antwerp in Belgium.
The find would be worth around £21 million to organised criminals as wholesale according to NCA, and in excess of £120 million at street level.
It was one of the largest seizures of heroin in the UK.
Once the drugs had been removed during the early hours of the following morning, the container was returned to the vessel which continued to Antwerp.
It docked there on 15th September and Dutch and Belgian law enforcement agencies kept the container under surveillance until it reached a warehouse south of the Hague in the Netherlands.
When it arrived, officers arrested the driver of the lorry and two men involved in unloading.
Back in the UK, Thames Valley Police arrested a 45-year-old man suspected to be a UK facilitator in the organised crime group.
He has since been released on bail.
Nick Holland, NCA Director of Investigations, said: "This is a huge seizure which has denied organised criminals tens of millions of pounds in profits, and is the result of a targeted, intelligence-led investigation, carried out by the NCA with international and UK partners.
"We know that a lot of these drugs would have ultimately been sold in the UK, through County Lines networks.
"There is violent competition between rival organised crime groups at all stages of Class A drug production and supply. The business model also involves the exploitation of vulnerable adults and children both in the UK and overseas.
"Policing colleagues are tackling street level County Lines gangs who dominate and intimidate UK communities, working closely with front line NCA officers who are taking action against the most controlling and most serious and organised criminals causing the most harm across the UK.
"By targeting those at the top of the chain and dismantling the County Lines business model, we reduce drug supply to the UK, making it an unviable business."
Both the seizure and arrests were the result of a partnership working with European law enforcement agencies.