WASHINGTON — The head of the Consumer Product Safety Commission conceded this morning the agency "hasn't been acting as quickly as it should" on crib safety problems.

Interviewed on morning news shows in the wake of the largest-ever recall of cribs, Chairman Inez Tenenbaum pledged the commission would "firmly but fairly" enforce a law Congress passed last year giving regulators greater authority to police the industry.

More than 2.1 million drop-side cribs by Stork Craft Manufacturing of Canada are being recalled following reports of four infant suffocations. The CPSC said the recall involves 1.2 million cribs in the United States and almost 1 million in Canada, where Stork Craft is based. Sales of the cribs being recalled go back to 1993 and nearly 150,000 of the cribs carry the Fisher-Price logo.

The agency said the drop-side cribs have a side that moves up and down to allow parents to lift children from the cribs more easily. It also said there have been 110 incidents of drop-sides detaching from the cribs.

Asked today whether people should abandon such cribs, Tenenbaum said she recommends that. And she said consumers also could order plastic kits from the manufacturer to immobilize crib sides.