The China Food and Drug Administration said on Thursday it did not find the two banned chemicals in a medical product that Hong Kong health authorities claimed contained the substances.

The Department of Health of the Hong Kong Special Administrative Region said on Tuesday that the Hospital Authority of Hong Kong warned the public not to buy Wei C Yin Qiao Pian, a popular cold treatment on the Chinese mainland.

They said it had tested positive for phenacetin and acinophenazone, two undeclared and banned chemicals, in one such product labeled as made by Tong'an Pharmaceutical, based in Shenzhen, Guangdong province.