The TGA is reviewing the safety of all metformin products after the Singaporean regulator recalled three medicines that contained traces of a carcinogen.

The move follows similar investigations by the US and European regulators, amid concerns more metformin products could be contaminated by N-nitrosodimethylamine (NDMA).

However, doctors have been urged to continue prescribing the drug until more information emerges.

The compound is commonly found in low levels in certain foods, such as smoked and cured meats, some drinking water and in air pollution.