Concern that US regulators may be too financially stretched to continue adequately to oversee the booming futures markets was thrown into focus on Friday when a top Democrat promised to investigate the issue.

Richard Durbin, senate majority whip, said he was concerned that a request by the White House to raise the budget of the Commodity Futures Trading Commission (CFTC) to $116m in fiscal 2008, from a current $98m, may not be enough to allow the regulator to continue being “the cop on the beat”.