Xinhua says Chinese health authorities downplayed the risk of the mosquito-borne virus spreading because of the winter cold.
China has confirmed its first case of the Zika virus in a man who had recently travelled to South America, the official Xinhua news agency reported.
The virus, which is causing international alarm after spreading through much of the Americas, was detected in a 34-year-old man from Ganxian county in the eastern province of Jiangxi, Xinhua said, citing China's National Health and Family Planning Commission.
Chinese health authorities downplayed the risk of the mosquito-borne virus spreading because of the winter cold, Xinhua added.
Hong Kong's Department of Health said in a statement that the man, who had travelled through the city on his return to China, worked in Dongguan, a bustling manufacturing city in the neighbouring southern province of Guangdong.
Hong Kong's Port Health Office has stepped up inspections at the airport in response and reinforced training for boundary control inspectors, the statement added.
There is a risk that Zika could be spread locally if it was introduced to Hong Kong, the statement said, because Aedes Albopictus mosquitoes, which transmit the virus, live there. But no cases of the virus in Hong Kong have been reported so far, it said.
The infected man had been quarantined at a hospital in his hometown since Feb. 6, Xinhua said, adding that he was recovering with normal body temperature and a fading rash.
Hong Kong Secretary for Food and Health Ko Wing-man told reporters that the bureau was seeking details of the man's travel history from the mainland authorities because he had transited through the city.
The risk of contracting the virus through human contact was low, so the bureau was not worried about the spread of the illness in Hong Kong, Ko said, but he added the authorities were monitoring the situation closely.
Mainland health authorities could not be immediately reached for comment.
Zika has spread quickly in South and Central America and the Caribbean, with Brazil the worst affected country.
The World Health Organization declared an international health emergency on Feb. 1 over the virus, citing concern over a possible link with a rise in cases of microcephaly, a birth defect characterized by an abnormally small head that can result in developmental problems.
Most infected people have no symptoms or mild ones including fever and skin rashes.