Federal product safety regulators are warning that parents immediately should stop using certain clip-on, tabletop chairs for infants and toddlers, and they say that the company that sells the items has refused to carry out a product recall acceptable to the agency.

The Consumer Product Safety Commission says that some of the “metoo” clip-on chairs from phil&teds USA Inc. of Fort Collins, Colo., “put young children at risk of serious injury due to multiple safety hazards.”

The product has a nylon seat for small children and a metal frame that is clamped onto tables with two metal vises. Among the hazards, the CPSC says, is that the clamps can become loose, sending a child tumbling to the floor and potentially causing head and other injuries. The agency said it is aware of “numerous incidents” — believed to be about a dozen, the Associated Press reports — in which children have been hurt.

In addition, the CPSC said, children are at risk of having their fingers pinched or even amputated if they become caught in the space between the chairs’ clamps and metal bars.

According to the CPSC, phil&teds has offered consumers a repair kit for the problem that provides “rubber boots” for the upper clamp grips of the chairs. However, despite a statement by the company that it was working “in cooperation with” the agency, the CPSC has not approved the kit.

“Even with those rubber boots, the chair can still slip off a table,” said a commission spokesman, Scott Wolfson. “We believe the company needs to come up with a free remedy that will prevent children from falling or having an amputation hazard if one side of the chair detaches.”

The AP said phil&teds did not respond to a call seeking comment from the company.

The “metoo” chairs have been on the market since May, 2006. They are sold at retailers such as Target and Toys R Us. The CPSC says tens of thousands already have been sold that present a danger to children.