WASHINGTON/NEW YORK (Reuters) – Senate Agriculture Committee Chairman Pat Roberts has asked for a full explanation from the U.S. Commodity Futures Trading Commission for an accounting error that led auditor KPMG to withdraw nearly a decade of financial opinions about the agency’s accounts. The Republican senator “has already begun inquiries at the CFTC for a full accounting” of the problem, a spokesperson for the committee, which provides Congressional oversight of the U.S. derivatives regulator, told Reuters on Wednesday.