Beijing responds to the Guardian's investigation that around one third of anti-malaria treatments were counterfeit

China has denied allegations that it has been exporting huge amounts of counterfeit medication to Africa, threatening public health in east Africa, five days after the Guardian published a front page exposé on the phenomenon.

The official Xinhua news agency said a foreign ministry spokeswoman rejected the accusation, but "called on foreign traders to procure medicines from legitimate companies through standardised channels".

"Spokeswoman Hua Chunying said at a daily press briefing that the accusations are unfounded, noting that co-operation between the Chinese government and African countries has played an important role in improving the healthcare environment for people in Africa," Xinhua reported on Thursday night.

The Guardian article cited experts and NGO reports as saying that up to a third of anti-malarial drugs in Uganda and Tanzania may be fake or substandard, and that the majority of them are manufactured in China and India. The drugs look identical to real ones, and can only be distinguished with lab testing. Aside from malaria drugs, analysis of antibiotics and contraceptives have also turned up fakes. "Some pills contain no active ingredients, some are partial strength and some the wrong formulation entirely," said the article.

The fake medications have led to deaths, prolonged illness and increased drug resistance in areas of east Africa, the article said.

A Chinese foreign ministry official refused to specify which parts of the Guardian article the ministry disputed. She said that the repudiations were aimed at the question of counterfeit drug exports, not the article specifically.

Counterfeit drugs are an endemic and long-running issue in China. According to official statements, Chinese police seized £113m worth of fake pharmaceuticals this July alone and £19m worth last November. Many ingredients were found to be harmful or toxic.

According to Xinhua, the foreign ministry spokeswoman "stressed that China always attaches great importance to drug safety and resolutely cracks down on the manufacture and sale of counterfeit drugs" and defended Beijing's record of providing healthcare aid to African countries.