GUANGZHOU, Dec. 11 -- Samples taken from two live poultry markets in south China's Guangdong Province have tested positive for H7N9 bird flu, the provincial health authority confirmed on Wednesday.

Three samples from the two live poultry markets, both in Shenzhen, tested positive, said the Health Department of Guangdong Province.

On Tuesday, a H7N9-control team collected 70 samples from 13 live poultry markets in Shenzhen.

The three samples were taken from a chopping board, chicken excrement and tools for removing feathers.

Guangdong health authorities warned the public to be aware of H7N9 transmission risks.

China on Tuesday confirmed three new cases, with two in Hong Kong and one in east China's Zhejiang Province. Local authorities have tightened prevention measures.

The Chinese mainland has so far reported 140 H7N9 cases, including 87 patients who have recovered.