Greenpeace Switzerland says a battle between the United States and the European Union over genetically modified (GM) foods could affect new Swiss laws.
The environmental group says a US complaint over the EU's ban on GM imports sends a clear signal to other countries not to impose similar restrictions.
Earlier this week, the US filed a case at the World Trade Organization (WTO), threatening trade sanctions against the EU unless it quickly lifts its ban on GM produce, imposed in 1998.
The dispute comes as Swiss politicians are debating a moratorium on GM agricultural produce.
"Switzerland is not under direct threat," said Bruno Heinzer, expert on genetic engineering at Greenpeace Switzerland. "But the US challenge is a very bad signal from our point of view."
Last week, the Swiss House of Representatives voted in favour of a temporary ban on genetically modified agricultural produce.
However, the decision to introduce a moratorium until 2010 still needs to be endorsed by the Senate.
Heinzer said the US challenge could influence voting in the Senate.
Since the US successfully challenged the EU's long-standing ban on sales of hormone-treated beef in the 1990s, no other WTO member has imposed one.
Biotech crops are engineered to repel predatory insects and better withstand the application of weed killers.
Critics say they could endanger human health and cause unforeseen damage to the environment.
Because GM soya and maize (corn) grown in the US is generally mixed in with non-GM material, huge amounts can no longer be sold in Europe.
The US exported $63 million worth of corn to the EU in 1998 but the exports dwindled to $12.5 million last year.
Last August some southern African nations facing famine rejected US food aid because it included genetically modified grain. Several countries later agreed to accept the products but only after they had been milled.
"All these regulatory measures are based on the precautionary principle," said Heinzer. "In Europe this precautionary principle is seen as normal behaviour with regard to human health or the environment.
"However from the US point of view, this is not a scientific approach."
Some analysts say the US move may be a bargaining card ahead of negotiations aimed at reforming global trade rules, including agriculture.
Swiss-listed agribusiness group, Syngenta, said the company was waiting for approval for several products which it had in the pipeline.
"We are not happy with the situation in Europe but we do not think this move by the US is the right way to go," said Syngenta's head of public affairs, Arthur Einsele. "It will not help create acceptance in Europe."
swissinfo, Vincent Landon
The Swiss House of Representatives has voted to introduce a moratorium on GM food until 2010.
The decision still has to be endorsed by the Senate.
The EU has refused to approve any GM products since 1998.
US farmers say the dispute has cost them about $300 million in lost sales, mostly corn, to Europe.