The Food Standards Agency (FSA) has confirmed it is investigating claims that benzene, a known carcinogen, could be present in soft drinks.
It comes as Germany's food watchdog, BfR, said it was examining soft drinks containing the common ingredients ascorbic acid (vitamin C) and sodium benzoate (E211), which can react together to form benzene.
Both authorities made the decision based on recent tests carried out in the US, which showed that some soft drinks contained the carcinogen above the country's legal limit for water. Further tests found two well-known drinks, also available in the UK, with levels three times the US's one part per billion limit.
The US authorities have now re-opened an investigation, closed 15 years ago, into benzene.