A man who first claimed to be poisoned when drinking a Sprite soft drink has admitted to putting mercury in the beverage container, the Beijing News reported on Friday.

Though the Beijing police refused to comment, saying the case is still under investigation, sources told the newspaper that it had confirmed the mercury was "injected into the container".

On Nov 7 last year, 21-year-old Ma Sai, a worker at the Xuanwu environment and sanitation bureau, was hospitalized for mercury poisoning after he drank a can of Sprite in a restaurant in Xidan, a shopping district in the capital.

Coca-Cola China, which manufactures the beverage, later paid 20,000 yuan (US$2,950) for Ma's month-long treatment.

Mercury, also known as quicksilver, is extremely toxic and can cause chest pain, cough and impairment of pulmonary function.

On Jan 17, Wang Chen, a 13-year-old student, became the second person to be hospitalized for mercury poisoning after drinking Sprite. On Feb 3, Coca-Cola China again released 20,000 yuan for the teen's treatment.

Days later, the police recovered a broken mercury thermometer from Wang's house. The teenager told the police he broke the thermometer on the night of Jan 16 and cleaned the quicksilver on the floor using his hand.

Doctors said the quantity of quicksilver in a thermometer is not enough to cause obviously damage to the human body.

Wang was discharged from the hospital on Feb 9, even as his parents were still worried about the teen's health since there is no safe mercury standard for children.

On Feb 2, Coca-Cola China released a statement on its website, saying the company's bottling system worldwide has very stringent quality control processes to ensure all products are safe for consumption and are in full compliance with the national food and beverage quality and safety standards.

On Feb 4, the police sent the metal packaging of the Sprite drink, which Ma consumed, to the Tianjin-based China Packaging Research & Test Center to analyze the inner coating, hermeticity and exterior appearance.

Police officers, Ma's family and representatives from the beverage magnate attended the test and agreed the results were "vital evidence" to prove whether or not the mercury was deliberately injected into the can.

The police have yet to reveal the results of the test.