Bulgaria has extradited to the United States an alleged accomplice of "cryptoqueen" Ruja Ignatova, who raised billions of dollars in a fraudulent virtual currency scheme before disappearing in 2017, prosecutors said Wednesday.

"A woman, who is a Bulgarian national and goes by the initials I.D., was handed over to representatives of the US authorities at Sofia airport on March 20," Sofia City Prosecution spokesman Hristo Krastev told journalists.

"The extradition was requested in connection with... participation in an organised criminal group involved in fraud and money laundering," he said, adding the women was an alleged accomplice of Ignatova.

Last June, the Federal Bureau of Investigation placed 42-year-old Ignatova on its 10 most wanted list and put up a $100,000 reward for her as the mastermind behind OneCoin -- one of the most notorious scams in the world of crypto currencies.

Ignatova launched OneCoin in 2014, collecting possibly more than four billion dollars through embezzlement.

The extradited woman was named as Irina Dilkinska in the indictment of the US district court of the southern district of New York, which was seen by AFP.

The Sofia Court of Appeal extradition ruling gives her age as 41.

Dilkinska's participation was "by, among other things, managing the scheme's proceeds and evading law enforcement investigations in the scheme" from 2014 to 2019, the indictment said.

She has been charged on two counts -- conspiracy to commit wire fraud and conspiracy to commit money laundering, with each of them carrying a maximum potential sentence of 20 years in prison, it added.

Ignatova disappeared in Greece in October 2017, just around the time US authorities filed a sealed indictment and warrant for her arrest. Her whereabouts remain unknown.

Several others, including her brother, have also been arrested in connection with the case.