Environmentalists are warning that Mexico, the cradle of corn, risks damaging its staple if the government gives US firms the green light to plant genetically-modified maize in huge swaths of land.

The agriculture ministry is examining the possibility of allowing Monsanto, DuPont and Dow to plant GMO corn in 2.4 million hectares (six million acres) of land, but no decision has been taken yet.

“Every indication shows that a decision could be taken in the coming weeks,” Silvia Ribero, a spokeswoman for the Canada-based ETC Group, which monitors the ecological impact of new technologies on poor regions, told AFP on Tuesday.

She said President Felipe Calderon could give his authorization before he leaves office on December 1. She noted that the sowing season starts next month.