The U.S. Securities and Exchange Commission (SEC) is heightening the scrutiny of the work audit firms do for cryptocurrency companies, a senior official of the regulator told the Wall Street Journal on Thursday.

"We're warning investors to be very wary of some of the claims that are being made by crypto companies," said Paul Munter, SEC's acting chief accountant in an interview with the journal.

The SEC did not immediately respond to a Reuters request for comment on the report.

The development comes as the implosion of FTX has rippled across the industry, hobbling liquidity at firms with exposure to what was once one of the world's biggest crypto exchanges, and has prompted investigations by regulators in several countries.

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 crypto firms have since been bracing for a fallout from the FTX collapse, with many counting their exposure in millions to the beleaguered exchange.