A “prolific money” launderer and her associates paid over £1.8 million into London high street banks in a period of just two weeks.
The money is believed to have come from drug dealers and was deposited in smaller amounts to avoid suspicion.
Launderer Fen Chen, her friend Ying Lin and two associates took bundles of bank notes into dozens of branches between 30 July and 15 August 2016.
Officers from the National Crime Agency arrested Chen after she took a bag containing more than £300,000 from Albanian Fation Koka in a supermakert car park.
More money and a cash counting machine were discovered at her flat, along with bank slips detailing hundreds of deposits totalling £1.8 million.
NCA operations manager Kevin Gee said: “Fen Chen was a prolific money launderer, able to process millions of pounds in cash in a very short period of time.
“Organised crime groups rely on money launderers like Chen, who play an integral part in allowing them to benefit from and re-invest their criminal profits.
“Taking money launderers out of the chain, as we have done here, makes life far more difficult and more risky for crooks trying to clean their dirty cash.”
Chen was jailed for six years and three months.
Lin was deported after being sentenced to 14 months in jail.