A woman dubbed the "cryptoqueen" for her role in a $4bn (£3bn) cryptocurrency scam has been sentenced to 20 years in prison.

Ruja Ignatova disappeared in 2017 with tens of thousands of investors' bitcoin and other digital currencies, in what prosecutors called one of the largest financial frauds in history.

Her accomplice, Konstantin Ignatov, was handed a 15-year sentence.

The pair, who are siblings, were convicted on multiple counts, including money laundering and wire fraud.

Ignatova and Ignatov operated a company called OneCoin, which they marketed as a new and revolutionary cryptocurrency. They promised investors huge returns on their money, but the entire scheme turned out to be a fraud.

According to the indictment, OneCoin was a pyramid scheme that relied on attracting new investors to generate profits rather than actual trading activity.

The pair reportedly defrauded investors out of over $4bn, with Ignatova alone pocketing around $500m.

Ignatova disappeared in 2017, leaving her brother Konstantin to face charges in the US. She was last seen boarding a flight from Sofia, Bulgaria, to Athens, Greece, and has not been seen or heard from since.

Her whereabouts remain unknown, but she has been dubbed the "cryptoqueen" due to her skillful manipulation of the cryptocurrency market.

Ignatov, who was arrested in March 2019, pleaded guilty to charges of conspiracy to commit wire fraud and conspiracy to commit money laundering. He had agreed to cooperate with authorities in exchange for a lighter sentence.

During the sentencing hearing, US District Judge Valerie Caproni said Ignatova had "destroyed people's lives" and that it was "not because of any fundamental misunderstanding of cryptocurrency trading, but because you knew it was based on lies."

Authorities believe that many of the investors were lured into the scam by Ignatova's charisma and promises of overnight wealth. However, the reality was much darker, with OneCoin's "virtual currency" unable to be exchanged for real money.