Colgate Palmolive, the US consumer products company, was on Thursday drawn indirectly into a mounting debate over the safety of food and consumer products imported from China, after it warned that counterfeit versions of its toothpaste being sold in the US contained a poisonous chemical.

The company said there were indications that small tubes of counterfeit toothpaste found in some “dollar stores” in the northeast US may contain diethylene glycol, a substance blamed last year for scores of deaths from contaminated Chinese-made cough medicine in several Central American countries.