The men, aged between 24 and 59, were arrested in dawn raids in London, Manchester, Leeds and five towns in northern England, the National Crime Agency (NCA) said
Thirteen men were arrested on Tuesday on suspicion of involvement in the biggest drugs racket ever uncovered in Britain, police said.
The suspects were allegedly part of an international organised crime group responsible for importing more than 50 tonnes of drugs, worth billions of dollars, into Britain from the Netherlands.
The men, aged between 24 and 59, were arrested in dawn raids in London, Manchester, Leeds and five towns in northern England, the National Crime Agency (NCA) said.
They are suspected of being part of the British arm of a group that used front companies to import heroin, cocaine and cannabis, concealed within truckloads of vegetables and juice.
Four men and two women were arrested in the Netherlands in April and are awaiting extradition to Britain as part of the same investigation.
"We believe we have dismantled a well-established drug supply route," said Jayne Lloyd, the NCA's regional head of investigations.
"We suspect these men were involved in an industrial-scale operation - the biggest ever uncovered in the UK - bringing in tonnes of deadly drugs that were distributed to crime groups throughout the country."
The men arrested Tuesday were held in connection with three consignments that were intercepted in September 2018, the NCA said.
That shipment contained 351kg of cocaine, 92kg of heroin, 250kg of cannabis and 1,850kg of hemp/hashish, with a total street value of more than $46.5 million.
Enquiries led officers to believe the men have imported drugs through British ports on several occasions between February 2017 and October 2018.
The NCA said the investigation was linked to an operation in which 13 individuals were sentenced to a total of 176 years in jail following the seizure of more than 100kg of heroin in 2015.