Green campaigners have called for an EU ban on neonicotinoid pesticides to be extended to wheat crops – prompting an angry response from farming leaders.

Three of the seed-treatment chemicals were banned on flowering crops such as oilseed rape in 2013, after concerns were raised about their impact on the health of bees.

But they can still be used on other crops and one – clothianidin – is widely used to protect wheat against pests such as barley yellow dwarf virus.

A Friends of the Earth report found the use of clothianidin on wheat also posed a threat to bees and other wildlife. It says treated seeds could be eaten by birds, or the chemical could leach into the soil where it could be absorbed by other plants, or into watercourses where it could harm aquatic invertebrates, with a knock-on impact on fish.

Friends of the Earth is urging Defra secretary Andrea Leadsom to support an extension of the current EU neonicotinoid ban to include wheat and all other crops.

But farming leaders said the move was 'not justified by the available scientific evidence' and could have serious consequences for the production of wheat.

Friends of the Earth nature campaigner Sandra Bell said: 'There is increasing scientific evidence that the use of neonicotinoids on wheat poses a threat to our bees, birds and butterflies – current restrictions on these pesticides must be extended to cover this crop.

'We can't afford to gamble with nature in this way if we are to carry on producing British food and safeguarding the health of our countryside.

'The UK government must back a complete ban on neonicotinoid pesticides – and commit to helping farmers to grow food without harming the environment as a central part of its post-Brexit farming policy.'

Guy Smith, vice president of the National Farmers' Union (NFU) and also chairman of next month's Norfolk Farming Conference, said: 'Friends of the Earth's latest idea to limit the use of neonicotinoids on wheat is not justified by the available scientific evidence and could have serious consequences for farmers' ability to grow food sustainably. With no restrictions of this kind anywhere else in the world farmers would be put at an extreme competitive disadvantage without the use of neonicotinoids on wheat.

'The fact remains there's still no clear evidence showing that neonicotinoids are responsible for widespread declines in bee and pollinator populations. The evidence shows that the major declines in pollinator biodiversity, and in populations of farmland birds like tree sparrows and grey partridge, pre-dates the introduction of neonicotinoids by a decade or more.

'Over 1.8m hectares of wheat are grown across the country and farmers increasingly use an Integrated Pest Management approach to make best use of all the tools available to them to protect their crop from pests. Seed treatments using the neonicotinoid insecticide clothianidin are an important part of this approach, to control aphids and the viruses they transmit, and in doing so help manage pest resistance and reduce the use of foliar insecticide sprays.'