Friends and foes of the use of genetic engineering in US agriculture have united in criticising two accidents in which a food crop was contaminated by a crop from the previous year designed to yield pharmaceutical products.

The US Department of Agriculture and the Food and Drug Administration announced last week that they had found such genetically modified corn growing in two soybean plots in the states of Iowa and Nebraska.

The GM corn had germinated from seeds left from 2001 plantings by the Texas-based company ProdiGene. The company was required to screen and remove these plants as part of its government permit.