A committee of centre-right and rightwing parliamentarians has called on voters to reject a moratorium on genetically modified products.
But the environmental group Greenpeace Switzerland said that traditional farming methods and genetically modified organisms (GMOs) cannot co-exist in agriculture.
The Swiss electorate is being asked on November 27 whether to accept a five-year moratorium on GMOs.
The cross-party committee of more than 100 parliamentarians said on Monday that the initiative was effectively a ban which treated farmers patronisingly, took away choice from consumers and threatened Switzerland's biotechnology research.
Helen Leumann, from the centre-right Radical party, told a media conference in Bern that the move to ban GMOs was superfluous because the country already had one of the strictest laws on GMOs in the world.
The Christian Democrats' Josef Leu, also on the centre-right, added that farmers would suffer. During these times of increased competition, it was important to let farmers make their own decisions about what products they wanted to sell, he said.
According to rightwing Swiss People's Party politician Hermann Weyeneth, the initiative has dishonest aims. He said that the moratorium was actually aimed at banning GMOs altogether, rather than for just five years.
Other parliamentarians raised concerns over the future of Swiss biotechnology research, saying a moratorium would send out the wrong signals and could lead to a loss of investment in the science.
Switzerland is among the top five biotech research countries worldwide.
Monday also saw Greenpeace Switzerland step up its campaign in favour of the moratorium. It had invited a Canadian beekeeper and organic advisor to talk about their experiences of GM crops.
The two Canadians said that beekeepers and farmers could no longer guarantee the purity of their products, because of cross-pollination between GM and non-GM crops in neighbouring fields.
Greenpeace Switzerland urged voters to reject GM farming at the ballot box.
"Little Switzerland wants to have organic farming which would give it market opportunities and which would allow farmers and the environment to come out the winners," Greenpeace said in a statement.
"It is an illusion to believe that bees would respect a 50-metre safety corridor. The example of Canada shows that bee populations fly across mountains and rivers. GMOs are living organisms," Greenpeace's Bruno Heinzer told swissinfo.
The Greenpeace position is supported by the centre-left Social Democrats and the Green Party. They deny the moratorium would have an impact on research.
The government recommends a "no" vote, as do many prominent Swiss scientists. The rightwing People's Party also came out against, while the centre-right Christian Democrats and the Radicals are likely to follow suit.
In 1998 Swiss voters overwhelmingly rejected a more far-reaching GM ban at the ballot box.
swissinfo with agencies
A popular initiative calling "for food produced without genetic modification" demands that all commercial use of GMOs be abandoned for a period of five years.
Parliament and the government have rejected the moratorium.
They consider that the current law on GMOs already adequately protects humans, animals and the environment.
This law, which came into force last year, outlaws the use of genetically modified animals and sets down strict guidelines for GM crops.