A top U.S. regulator has said that while her agency is dealing with several major cases, it is too numerous to police all cryptocurrency fraud.

Christy Goldsmith Romero, one of the five commissioners of the U.S. Commodity Futures Trading Commission (CFTC), said cryptocurrency cases make up about 20 percent of the agency's portfolio, These include recent civil cases against the exchanges Binance and FTX.

"There's a lot of fraud in this space," Goldsmith Romero said at the New York City Bar Association's white collar crime conference. "We can't police all fraud, but we have to do something."

CFTC Chairman Rostin Behnam has sought greater authority from lawmakers for the agency to oversee the spot cryptocurrency market.

Goldsmith Romero dismissed the notion of a "turf war" between the CFTC and the SEC over cryptocurrency regulation, but acknowledged that many products in the industry are new and agencies are "still trying to figure it out."

She also said that cryptocurrency companies should not view the CFTC as a friendlier regulator than the deep-pocketed SEC.