Four Albanians were handcuffed during a police operation in Tottenham, where large amounts of undeclared money were also seized.
British media reports that a 48-year-old Albanian man was arrested in Dover with a bag full of 200,000 pounds that, according to the National Crime Agency, was headed for Albania.
Also, a few moments later, three other citizens, aged 34, 22 and 17, were arrested with around 150,000 pounds hidden in the car.
The NCA said it had been investigating this group of Albanians for two years.
Officers claim the Albanian gang operates under the guise of a legitimate courier company, but specializes in transferring illegal money out of the country from other gangs run by Albanians.
"Money launderers enable other serious and organized criminals, such as drug and firearms dealers, to carry out their illegal activities which seriously damage our society," said NCA Operations Manager Paul Orchard.
The investigations started in 2022 when two of the Albanians were detained again after being caught with significant amounts of undeclared money.