More than 2.1 million drop-side cribs associated with the deaths of a dozen children over 16 years are being recalled as part of the biggest crib recall in U.S. history.

The U.S. Consumer Product Safety Commission said late Monday the recall involves 1.2 million cribs in the United States and almost 1 million in Canada. All of the cribs are made by Canada-based Stork Craft Manufacturing. The cribs being recalled date back to 1993.

Nearly 150,000 of the cribs carry the Fisher-Price logo.

The head of the Consumer Product Safety Commission says the agency should be doing a better job dealing with safety problems.

Her comments come a day after the agency announced the largest-ever crib recall. More than 2.1 million drop-side cribs are being recalled after reports that four babies suffocated. The recalled cribs are made by Stork Craft Manufacturing of Canada.

CPSC chairman Inez Tenenbaum is now advising consumers against using any drop-side cribs. She's urging people to order plastic kits from the manufacturer to immobilize the crib sides.

The concern is that the drop-side can detach, creating a dangerous space that can trap a child.

Tenenbaum is also vowing that her agency will enforce a law passed last year giving it greater regulatory authority. She appeared on the morning news shows.

The CPSC said it is aware of four infants who suffocated in the drop-side cribs, which have a side that moves up and down to allow parents to lift children from the cribs more easily.

The Stork Craft cribs have had problems with their hardware, which can break, deform or be lost after years of use. CPSC said problems also can arise because of assembly mistakes by crib owners. These problems can cause the drop-side to detach and create a dangerous space between the drop-side and the crib mattress, where a child could become trapped.

The commission is urging parents to stop using the cribs until receiving a free repair kit from Stork Craft.

The cribs, manufactured and distributed between January 1993 and October 2009, were sold at major retailers including BJ's Wholesale Club, Sears and Wal-Mart stores and online through Target and Costco. They sold for between $100 and $400 and were made in Canada, China and Indonesia.

Some of the recalled Stork Craft cribs may be for sale at second-hand stores, and those stores are being held accountable, said Patty Davis, a spokesperson for the CPSC.

"It's illegal," Davis said. "We're holding resale stores accountable."Likewise, parents should not be selling their used recalled cribs at yard sales, Davis advised.

"We don't patrol yard sales, but what we advise consumers to do is check to see if the product has been recalled, and to do the responsible thing," she said. "Don't pass on a hazard to another child. This crib is a hazard. There are four infants who have died in this recalled Stork Craft crib with the drop-side."

Consumer advocates have complained for years about drop-side cribs. More than 5 million of them have been recalled over the past two years alone, associated with the deaths of a dozen young children.

ASTM International, an organization that sets voluntary industry safety standards for a broad range of products that includes such disparate products as toys and steel used in commercial buildings, approved a new standard last week that requires four immovable, or fixed, sides for full-sized cribs which essentially eliminated the manufacture of new drop-side cribs.

CPSC also is considering new rules for making cribs safer and could adopt the ASTM voluntary standard as a mandatory one, which would outright ban the cribs.

Toys R Us started phasing out drop-side cribs this year and no longer will carry them next month.

FoxNews.com's Jessica Ryen Doyle and The Associated Press contributed to this article.