Police say they have broken up a gang responsible for more than a quarter of the counterfeit money seized in the UK.
The gang are accused of supplying fake £20 notes
Detectives from City of London Police - which led the operation - estimated that over the past four years the gang had supplied about £10m in fake notes.
As well as £20 and £50 notes, the gang dealt in Scottish banknotes and Euros.
Four men and two women have been arrested after raids at two homes and a business in Essex; one man was held after a 45-minute car chase.
Officers have described it as the "most significant" operation in their history to detect counterfeiting.
When police arrived at one business address in Dagenham they found printing presses in operation.
Man, 35, from Rainham, Essex
Woman, 27, from Rainham, Essex
Man, 46, from Canning Town, London
Woman, 60, from Canning Town, London
Man, 27, from Dagenham, Essex
Man, 56, from Dagenham, Essex
One of the suspects escaped in a car. He was followed for 45 minutes by five police cars from three different forces and two helicopters, before eventually pulling over and giving himself up.
The raids arose from an investigation run by the Central Detective Unit from the City of London Police, the Bank of England and the Serious Organised Crime Agency.
Detective Inspector Dave Clark said: "Although the currency seized is not of high quality, it is still possible to pass these notes off as genuine to unsuspecting people.
"The City Police operation was the second of its kind within the last month and, together, has been responsible for the removal of a significant element of the UK's counterfeit currency."
The suspects, aged between 27 and 60, were from Rainham and Dagenham in Essex, and Canning Town in east London.