Authorities in Canada and the United States are warning against the use of a brand of children's high chairs due to a risk that the seats may come loose or detach. 

Health Canada and the U.S. Consumer Product Safety Commission say Graco Classic wooden high chairs pose ``a fall hazard to the child'' and are being voluntarily recalled by the company.

The agencies say there have been nine reports of children falling from the chairs as a result of the flaw, leading to bumps, bruises and scratches and in one Canadian case, a concussion. 

They say there have been 58 reports of the seats loosening or detaching. 

Roughly 3,400 of the chairs have been sold in Canada and another 86,000 in the U.S. 

The products were sold at Babies R Us, Burlington Coat Factory and other nationwide retail stores, as well as online at Target.com, Walmart.com and other online stores, between September 2007 and December 2010.

Photo: Graco website