Genes from genetically-engineered corn have been found in traditional crop strains in Mexico, according to a new study likely to reignite a bitter controversy over biotech maize. The paper, by scientists from Mexico, the United States and the Netherlands, backs a 2001 probe that sparked a row over the safety of genetically-modified (GM) crops.

Green activists say GM crops are a potential hazard, arguing that their genes could spread to related plants through cross-pollination.