The law is aimed at fixing the conditions under which genetically modified (GMO) crops may be cultivated in France, where many regard them with deep suspicion.

Europe has demanded that member states formulate domestic laws on GMO use since 2001 but France has dragged its feet over an issue that is fiercely disputed by supporters including the main farmers union and environmentalist opponents.

The bill that passed the lower house would toughen penalties for deliberately damaging GMO crops, a favourite tactic of protestors such as veteran environmentalist Jose Bove, setting fines of 75,000-150,000 euros with prison terms of two to three years.

Greenpeace denounced the proposed law, which it said would benefit "a handful of industrialists" and said amendments introduced during the lower house reading would have no more than a "cosmetic" effect.

As well as strong opposition in parliament from the left wing Socialists and the Greens, the bill has caused an outbreak of infighting in the ruling UMP party.

Centre-right deputies attacked junior environment minister Nathalie Kosciusko-Morizet for allowing an opposition-backed amendment to make it into the text voted by the lower house.

The amendment would impose strict environment and public health restrictions on GMO crop cultivation but is likely to be overturned in the Senate.