WASHINGTON -- The Consumer Product Safety Commission said Thursday that Ross discount department stores had agreed to pay a $3.9 million fine for failing to report that it continued to sell defective children's clothing after the agency warned that the clothes could cause injuries or strangulation deaths.

According to the settlement, Pleasanton-based Ross Stores knowingly failed to report to the commission within 24 hours that it had sold or kept in its stores from January 2009 to February 2012 about 23,000 children's jackets and sweatshirts that had drawstrings at the neck or around the waist.

The company had previously paid a $500,000 fine for not reporting that it was selling the defective clothing. The commission said the current penalty was the second-largest in the agency's history. The agency said there were no reported injuries or deaths from the Ross clothing sales.

The commission is increasing its efforts to go after companies for not reporting problems with defective products. A 2008 law gave the agency authority to increase penalties.

"Companies should know that there are serious consequences for not telling CPSC about a product that can put a child in harm's way," said Inez Tenenbaum, chairman of the safety commission. "Ross is being held accountable for not following the law and for not complying with a federal standard that is child-protective."

The company did not respond to requests for comment.

The commission said it warned clothing stores as early as 1996, after the deaths of several children, that children's clothes with drawstrings were defective and present a substantial risk of injury to young children.

One child died after a drawstring got caught on a playground slide. Another died after a drawstring was caught in a school bus door and the child was dragged to death. The commission said that since 1985 it has received reports of 84 injuries to children, including 26 who died, after the drawstrings on their clothing got stuck.

STM International, an organization that develops and publishes voluntary technical standards for a wide range of products, followed up with additional voluntary standards in 1997.

In 2011, the safety commission created mandatory rules, which called the drawstrings a substantial hazard. The rule allowed the commission and the Customs and Border Protection to stop shipments of potentially hazardous children's clothing at ports of entry.

The commission said that, even under the old voluntary standards, companies were still required by federal law to report problems, complaints and injuries resulting from defective products.

In agreeing to the settlement, Ross denied that it had knowingly failed to inform the commission about the clothes. The store has agreed to create a compliance plan to keep similar incidents from happening. The company, which operates more than 1,000 stores in 29 states, is the third-largest discount retailer in the United States, behind T.J. Maxx and Marshalls.