Britax Child Safety Inc. (search) is recalling 355,516 child seats because a harness can loosen and endanger the child, the government said Wednesday.

Britax is recalling all Marathon, Husky, Wizard and Snug Seat Traveler Plus (search) seats. The seats were made between August 2002 and this July and have the model numbers E9L06, E9L30, E9L07 and E9L32, the National Highway Traffic Safety Administration (search) said.

Britax said no injuries have been reported because of the defect, which was discovered during company testing. Britax found that the adjuster strap could slip within the metal buckle that controls the tightness of the shoulder harness. If the strap slips far enough, the harness could loosen and the child could fall forward in an accident.

Britax will provide consumers with a free kit that will allow them to fix the problem by replacing the adjuster strap. Registered owners should receive the kit by Sept. 30. Consumers who did not register should call 800-683-2045 to receive a kit.

In the meantime, Britax said consumers should check to see if the strap is slipping and should use a different seat if it is.

Britax said seats made after Aug. 1 are not affected. The company also said it is recalling all seats not yet purchased and retrofitting them with the new strap. A spokeswoman for the company could not immediately say how much the recall will cost.

Britax recalled 2,689 Super Elite child seats last October because it also allowed children to move too far forward to meet federal safety standards. Agency spokeswoman Liz Neblett said the new recall is unusually large.

The agency has given high grades to the popular Britax seats in its safety seat ratings, which compare the assembly and ease of use of various seats.