Swiss environmental organisations have repeated their calls for the government to impose a moratorium on genetically modified organisms (GMOs).
They say proposals by the Senate to impose tight controls on growers of GM plants do not go far enough.
Organisations including Pro Natura and the Swiss branch of the World Wide Fund for Nature want a clearly defined, legal moratorium.
During their discussion on legislation governing gene technology, members of the Senate said their criteria were so strict, it would be impossible to grow genetically modified plants in Switzerland and that this amounted to a de facto moratorium.
Environmental bodies have repeatedly warned of the dangers of GM plants. They say GM crops could not only affect other plants but also pose a danger to animals like butterflies and birds.
A Swiss parliamentary commission charged with investigating the issue has recommended that tight controls be imposed on the use of GMOs but stopped short of calling for a complete ban.