The top U.S. derivatives regulator said his agency lacks resources to conduct even routine inspections of the exchanges and other companies it polices.

"We simply can't get into these entities on a regular basis," Commodity Futures Trading Commission (CFTC) Chairman Timothy Massad told lawmakers in Washington on Tuesday, speaking two weeks after the arrest of a trader accused of manipulating a futures market over five years. "We don't even get to many of the clearinghouses and exchanges once a year. That is a big problem," Massad said, as he asked for more money.

The CFTC is under scrutiny amid last month's allegations that Navinder Singh Sarao cheated on CME Group Inc.'s exchange from 2009 to 2014, including on the day of the 2010 "flash crash" that briefly erased almost $1 trillion from U.S. stock prices. Massad has responded to questions about Sarao by highlighting funding woes at the CFTC, pointing out that it's tasked with regulating the $700 trillion swaps market on a $250 million annual budget.