A grain vendor in the city of Shenzhen in south China's Guangdong province on Wednesday denied accusations that the company has sold rice contaminated with heavy metals.

Shenzhen Cereals Group Co Ltd purchased 13,584 tons of rice from a supplier in central China's Hunan province in May 2009. However, the rice was found to contain excessive amounts of cadmium and subsequently returned to the supplier, said Wang Huimin, a senior official from the company at a press conference.

Wang also showed reporters a testing report, return agreement and delivery bill for the returned rice.

"Our company does not know how the supplier in Hunan handled the rice after we returned it," said Wang, adding that the company has rarely purchased rice from Hunan since then.

Wang made the statement after the Nanfang Daily reported on Wednesday that the company has sold multiple batches of rice produced in Hunan province that contained excessive amounts of cadmium.

The report claimed that the company, a major grain dealer in the city of Shenzhen, sold the substandard rice bought in 2009 because of recent price hikes.

Netizens have reacted strongly to the incident, with some raising concerns that the contamination may have resulted from polluted water or farmland.