A senior official at the regulator told the Wall Street Journal that the SEC of the U.S. Securities and Exchange Commission is investigating the work audit firms do for cryptocurrencies companies.
Paul Munter, SEC's acting chief accountant, said, "We're warning investors to be very cautious about some of the claims being made by the companies we're talking about."
The implosion of FTX has sparked investigations in several countries and has resulted in the collapse of liquidity at firms with exposure to one of the world's biggest criptocurrency exchanges.
Last month FTX filed for U.S. bankruptcy protection and its founder Sam Bankman-Fried resigned as chief executive after rival exchange Binance walked away from a proposed acquisition.
Several firms have been bracing for a fallout from the FTX collapse, with many counting their exposure in millions to the beleaguered exchange.