A Chinese national has been convicted of playing a key role in what is believed to be the single largest cryptocurrency seizure in the world, worth more than £5.5bn ($7.4bn).

Zhimin Qian, also known as Yadi Zhang, pleaded guilty on Monday at Southwark Crown Court, London of illegally acquiring and possessing the cryptocurrency.

Between 2014 and 2017, she led a large-scale scam in China by cheating more than 128,000 victims and storing the stolen funds in bitcoin assets, the Metropolitan Police said in a statement.

The Met said the 47-year-old’s guilty plea follows a seven-year probe into a global money laundering web.

Qian had been “evading justice” for five years up to her arrest, which required a complex investigation involving multiple jurisdictions, said Detective Sergeant Isabella Grotto, who led the Met’s investigation.

She fled China using false documents and entered the UK, where she attempted to launder the stolen money by buying property, said the Met.

She had help from another Chinese national, Jian Wen. The former takeaway worker was jailed for six years and eight months last year for her part in the criminal operation.

“Bitcoin and other cryptocurrencies are increasingly being used by organised criminals to disguise and transfer assets, so that fraudsters may enjoy the benefits of their criminal conduct,” said Robin Weyell, deputy chief Crown prosecutor for the Crown Prosecution Service.

“This case, involving the largest cryptocurrency seizure in the UK, illustrates the scale of criminal proceeds available to those fraudsters.”

Monday’s conviction marks the “culmination of years of dedicated investigation”, which has involved the police and Chinese law enforcement teams, said Will Lyne, the Met’s Head of Economic and Cybercrime Command.

The Crown Prosecution Service (CPS) is working to ensure the fraudsters do not get hold of the stolen funds, the statement added.

The CPS said last year that many of the victims had some of their money returned to under a compensation scheme established in China.

Qian is being held in custody ahead of sentencing. The date of her sentencing has yet to be fixed.