European moves to temporarily ban the use of three insecticides linked to declines in bee populations have been met with legal action from two of the world’s biggest agricultural companies.

Syngenta, headquartered in Basel, Switzerland, said yesterday that it was challenging the European Commission’s ban on the controversial ‘neonicotinoid’ pesticides. The ban, which comes into force on 1 December, will last two years and cover three neonicotinoids: clothianidin, imidacloprid and thiamethoxam.

In a statement, the company said the commission’s decision was taken “on the basis of a flawed process”. John Atkin, the company’s chief operating officer, added that the commission was wrong to link thiamethoxam to declines in bee health.

Syngenta is challenging the thiamethoxam ban only, but another company — Bayer CropScience of Monheim, Germany — said yesterday that it had also begun legal action challenging the ban on all three chemicals. In a statement, it said that the Commission’s move is “unjustified, disproportionate and goes beyond the existing regulatory framework”.

A body of scientific evidence from laboratories studies shows that these chemicals can have a negative impact on bee health. A number of researchers have advocated that their use be restricted, according to the precautionary principle. But other scientists say that some of the laboratory research on the subject doesn’t necessarily reflect the real situation out in the field (see ‘Europe debates risk to bees‘).

A spokeswoman for the European Commission said that its measures were based on scientific information and the conclusions of the European Food Safety Agency, which has ruled that these insecticides could pose a risk to bees in some circumstances (see ‘Reports spark row over bee-bothering insecticides‘).

Corrected 28/8/2013: this blog post originally said Bayer began its legal action in May. The Commission decision was in May. Bayer began its action this month.