Claire Doole reports on Switzerland's deep divide

Voters are deciding whether more stringent restrictions should be placed on scientists. Opponents say the proposed changes will have far-reaching implications for the country's future as a biomedical research centre.

Consumers are concerned about the safety of food with genetically engineered ingredients

If approved, the new law will ban all research with genetically modified animals and crops. It would also forbid patents for genetically altered plants or animals.

The broad alliance of environmentalists and animal rights activists who are behind the referendum oppose any measures which tamper with nature.

Rudi Bowerman "Keep mother nature as it is"

President of Switzerland's Green Party, Rudi Bowerman, says food production should be in the hands of farmers and not scientists.

"I think it is much better to keep mother nature as it is and not to influence more than is necessary."

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Religious and some consumer groups are also concerned about the pace of scientific research.

But the proposed ban has sent a shudder through Switzerland's huge pharmaceutical industry.

Joining forces with the Swiss federal government and the medical profession, the industry says a ban will be economically and culturally disastrous.

Alex Mauron "The referendum is a prohibition on the right to gather knowledge"

Bio-ethics professor at Geneva University, Alex Mauron said: "If this referendum passes we will see many researchers voting with their feet as it were, namely moving abroad and taking away their research expertise and teaching talents which will be devastating and have very serious effects on the Swiss health system."

Swiss citizens are deeply divided

Recent polls indicate that 35% of people will vote for the law, with 15% voting against. But with half the population still undecided, the result is expected to be a very close call.

The Swiss have until Sunday afternoon to cast their vote. The BBC correspondent in Berne, Claire Doole, says the referendum has split the nation down the middle.