A member of the US Securities and Exchange Commission has thrown the latest round of punches in an ongoing turf fight between the SEC and a panel of financial-industry overseers, charged with deciding which financial firms should be labeled as systemically risky and subject to stricter oversight from the Federal Reserve.

Luis Aguilar, a Democrat on the five-member SEC, said in prepared remarks to the Mutual Fund Directors Forum Wednesday that the SEC's authority as the primary regulator of the mutual fund industry had been "undercut" by the Financial Stability Oversight Council and its research unit, the Treasury Department's Office of Financial Research.