US firm Pioneer Hi-Bred supplied the NK603 seed although it said the level of contamination was ‘minute'.

A little less than 2,000 hectares were said to have been sown in Bavaria, Baden-Wuerttemberg and Lower Saxony.

But environmental group Greenpeace argued it was closer to 3,000 and accused officials of knowing about the contamination in early March.

Farmers could now be hit with huge losses because harvested crops will have to be destroyed.

According to Greenpeace, up to 0.1 per cent of the yield is anticipated to have been contaminated in affected fields.

However Pioneer Hi-Bred has hit back saying the figure is closer to 0.03 per cent.

Lower Saxony's Environment Ministry reassured farmers that it was possible to stop the uncontrolled spread of the GM maize.

A spokeswoman for the ministry added that the contamination originated from two sacks of seeds although it is not clear how the mix up occurred.