US lawmakers plan to scrutinise the relationship between former MF Global chief executive Jon Corzine and the credit-rating firms that downgraded the brokerage as it hurtled toward bankruptcy, according to a person familiar with the matter.

The House Financial Services Committee announced this week that it had asked Corzine and regulators to attend a December 15 hearing to "focus on decisions and events leading to the collapse of MF Global" and "the effectiveness of regulators in overseeing MF Global's activities."