Beijing - Prices of star anise have risen by up to 50 per cent in some Chinese cities amid high demand for the popular cooking spice due to a belief that it may help prevent flu, state media said on Wednesday.

Retailers in Shanghai and other large cities reported star anise prices jumping from around 9 yuan (1.3 dollars) per kilogram to as much as 14 yuan (2.1 dollars) per kilogram, the China Daily newspaper said.

In the south-western region of Guangxi, which produces some 85 per cent of the world's star anise, wholesale prices have risen from 7 yuan to about 10 yuan per kilogram, said Li Yi, who heads the regional spice industry association.

"Many people come to buy it because they believe star aniseed will help with the flu," spice retailer Zhou Gendi told the newspaper.

Health Minister Chen Zhu last week suggested that pork cooked with star anise would be safer and that the spice would "certainly be a good treatment for the flu."

An extract from the spice is also one ingredient of Tamiflu, the antiviral drug marketed by Roche for use against the H1N1 flu virus, the newspaper said.

China has reported no confirmed cases of swine flu, but it has drawn criticism for its tough quarantine measures used against nationals of Mexico and other nations where cases have been reported.

A 25-year-old Mexican man was confirmed as infected with the virus after he landed in Shanghai and travelled on to Hong Kong last week.

The infected man remained in quarantine at a Hong Kong hotel on Wednesday, while a Mexican plane flew home 126 Mexican citizens, most of whom had been quarantined in Hong Kong and three mainland Chinese cities. (dpa)