A total ban on bee-harming pesticides in the countryside across Europe will be supported by the UK and kept in place after Brexit, the Environment Secretary has said.
In a reversal of the Government's previous position on "neonicotinoid" pesticides, Michael Gove said new evidence indicated the risk to bees and other insects from the chemicals was "greater than previously understood".
The science justifies the further restrictions on their use which have been proposed by the European Union, and unless the evidence changes the Government will maintain the controls post-Brexit, he said.
Since 2013, the EU has banned three neonicotinoids for use on certain crops such as oil seed rape, after authorities identified risks to honey bees.
The UK Government initially opposed the ban, claiming there was not enough evidence that bees were harmed by the pesticides, but other member states disagreed and the ban was implemented across the EU.
The European Commission has since proposed restricting the three neonicotinoids to only allow use on plants in greenhouses, which would extend the ban to crops such as sugar beet and winter cereals with seed treated with the chemicals.
Research estimates the value of the UK's 1,500 species of bees, butterflies and other pollinating insects to crops as being around £400 million to £680 million a year due to increased productivity. They are also a key part of wildlife food chains.
Mr Gove, a leading Brexiteer, said he wanted to see a "Green Brexit" in which environmental standards were not only maintained but enhanced.
"The weight of evidence now shows the risks neonicotinoids pose to our environment, particularly to the bees and other pollinators which play such a key part in our £100 billion food industry, is greater than previously understood.
"I believe this justifies further restrictions on their use. We cannot afford to put our pollinator populations at risk."
He added: "I recognise the impact further restrictions will have on farmers and I am keen to work with them to explore alternative approaches both now and as we design a new agricultural policy outside the European Union."
The Environment Department's (Defra) chief scientific adviser Professor Ian Boyd said: "The important question is whether neonicotinoid use results in harmful effects on populations of bees and other pollinators as a whole.
"Recent field-based experiments have suggested these effects could exist. In combination with the observation of widespread and increasing use of these chemicals, the available evidence justifies taking further steps to restrict the use of neonicotinoids."
Research last month found three-quarters of the honey produced worldwide contains neonicotinoids, highlighting how widespread they had become in the environment.
Separate research published in October revealed 76% of flying insect biomass in German nature protection areas had been lost in 30 years, while ongoing monitoring shows falls in many species of insects in the UK in recent decades.
Evidence has increasingly linked neocotinoids with declines in bees, with one recent paper suggesting one of the pesticides can potentially wipe out common bumblebee populations by preventing the formation of new colonies.
Environmental campaigners have long called for a total ban on neonicotinoids on farm crops in Europe, and welcomed the move by the Environment Secretary. But concerns have been raised that a ban will mean farmers using other harmful chemicals in their place.