Binance chief Changpeng Zhao stepped down and pleaded guilty to breaking US anti-money laundering laws as part of a US$4.3 billion settlement resolving a years-long probe into the world's largest crypto exchange, prosecutors said on Tuesday.

The deal, which will see Zhao personally pay US$50 million, was described by prosecutors as one of the largest corporate penalties in US history.

But several legal experts said it was a good outcome for Zhao, leaving his vast wealth intact and allowing him to retain his stake in Binance, the exchange he founded in 2017.

Binance broke US anti-money laundering and sanctions laws and failed to report more than 100,000 suspicious transactions with organisations the US described as terrorist groups including Hamas, al Qaeda and the Islamic State of Iraq and Syria, authorities said.

The exchange also never reported transactions with websites devoted to selling child sexual abuse materials and was one of the largest recipients of ransomware proceeds, they said.

“Binance made it easy for criminals to move their stolen funds and illicit proceeds on its exchanges,” US Attorney General Merrick Garland said on Tuesday. “Binance also did more than just fail to comply with federal law. It pretended to comply.”

The Justice Department, which negotiated the settlement with the Commodity Futures Trading Commission (CFTC) and the Treasury Department, is seeking an 18-month prison sentence for Zhao, the maximum suggested under federal guidelines, the New York Times reported.

Binance's former chief compliance officer Samuel Lim was charged by the CFTC, the agency said. Neither Lim nor his lawyers immediately responded to requests for comment.

Binance will pay US$1.81 billion within 15 months, and a further US$2.51 billion forfeiture as part of the deal, prosecutors said.

Zhao, a billionaire who was born in China and moved to Canada at the age of 12, pleaded guilty in a Seattle court on Tuesday afternoon.

"Today, I stepped down as CEO of Binance," Zhao said in a tweet after the settlement was announced. "Admittedly, it was not easy to let go emotionally. But I know it is the right thing to do. I made mistakes, and I must take responsibility. This is best for our community, for Binance, and for myself." (Reuters)