(Reuters) - Getting better access to information on derivative transactions was a "critical" factor in U.S. regulators' efforts to curb market abuses, Securities and Exchange Commission Chairman Mary Schapiro told Bloomberg in an interview.

Regulators needed information "that allows us to construct an audit trail, so that we can find insider trading, manipulation and other concerns that can reverberate through the entire marketplace," the news agency quoted Schapiro as saying.

That ability "is really going to be critical," she said.

Schapiro told a Senate panel in June that inquiries were being "seriously complicated" by difficulties identifying derivatives investors and determining the size of their trades.

Derivatives are financial instruments that derive value from an underlying asset. Credit default swaps, a type of derivative used to insure against debt defaults and speculate on a borrower's credit quality, were central to the credit crisis that led to the global economic downturn.

(Reporting by S. John Tilak in Bangalore; editing by John Stonestreet)