Indicted FTX cryptocurrency exchange founder Sam Bankman-Fried has pleaded not guilty to new US charges of conspiring to violate campaign finance laws and bribe Chinese authorities.

Bankman-Fried, 31, entered the plea to the new, 13-count indictment through his lawyer, Mark Cohen, at a hearing before US District Judge Lewis Kaplan in Manhattan federal court.

He had earlier pleaded not guilty to eight counts of fraud and conspiracy for allegedly stealing billions in FTX customer funds to plug losses at his hedge fund, Alameda Research.

Mr Cohen said he was planning to challenge the new charges because they were brought after Bankman-Fried was extradited from the Bahamas, where he was arrested in December and where FTX was based.

The new charges add to the pressure on Bankman-Fried, who faces a possible sentence of decades in prison if convicted at a trial set to start on October 2.

Bankman-Fried's arrest came after a flurry of customer withdrawals spurred by concerns about commingling of funds between the exchange and Alameda prompted the collapse of now-bankrupt FTX.

The initial indictment by the US Attorney's office in Manhattan contained few details about the alleged scheme.

In an unusual post-arrest blog post, the former billionaire acknowledged inadequate risk management at FTX, but said he did not steal funds.

Prosecutors in late February filed a new 12-count indictment elaborating on the fraud charges and accusing Bankman-Fried of illicitly contributing tens of millions of dollars to US political campaigns through straw donors, part of a strategy to buy influence in Washington.

And on Tuesday, prosecutors moved to unseal yet another indictment, which accused Bankman-Fried of conspiring to violate an anti-bribery law by orchestrating a $US40 million payment to Chinese authorities to regain access to $1 billion in cryptocurrency in Alameda accounts that had been frozen.

Three former members of Bankman-Fried's inner circle — former Alameda CEO Caroline Ellison, former FTX technology chief Zixao "Gary" Wang, and former FTX engineering director Nishad Singh — have all pleaded guilty and agreed to cooperate with prosecutors.

Bankman-Fried is confined to his parents' Palo Alto, California, home on $250 million ($373 million) bond pending trial.

Earlier this week, Judge Kaplan approved modifications to Bankman-Fried's bail package that are designed to prevent the defendant from tampering with witnesses.

Reuters