A pesticide that is lethally toxic to bees has been approved for emergency use in the UK for a fourth year in a row, sparking anger from environmental groups who described it as a “death blow” to the pollinating insects.

The Government said the neonicotinoid can be used on sugar beet “because of a danger that cannot be contained by any other reasonable means”.

Farmers use the pesticide to kill aphids that can spread the beet yellow virus and the Government said it wants to protect their livelihoods.

Thiamethoxam was banned in the UK and EU in 2018 and environmental groups have accused the Government of falling behind on aims to reduce pesticides by allowing its continued use.

The Government said there will be restrictions in place limiting its use and that allowing it is necessary to protect the British sugar industry.

Farming minister Mark Spencer said: ”We recognise the damaging impact that an outbreak of beet yellow virus could have on farmer livelihoods. We therefore regard issuing an emergency authorisation as a necessary and proportionate measure.

“The product can only be used if a threshold is met, and its use will be strictly controlled. This decision is based on robust scientific assessment and the risks have been evaluated very carefully.”

The Government said sugar beet supports 10,000 jobs and the virus can reduce crops by 50%, with a quarter of the national crop lost in 2020 to the virus at a cost of £67 million.

Barnaby Coupe, land use policy manager at The Wildlife Trusts, said: “The farming minister’s decision to authorise the use of a banned neonicotinoid pesticide on sugar beet for the fourth year in a row is a death blow for wildlife, a backwards step in evidence-based decision making, and a betrayal of farmers who are producing food sustainably.

“The Wildlife Trusts are deeply disappointed that this decision ignores a third of sugar beet farmers in England who chose not to use this chemical in previous years, and who will now be actively disadvantaged this year.

“It is entirely possible to produce food in a way that helps rather than harms nature – and UK farmers know that the use of this chemical is not a long-term solution.”

Conservationists are incensed at the Government for approving the pesticide on the same day that the Office for Environmental Protection found it to be largely off track in achieving its targets to improve the natural environment.

Bees and other pollinating insects are vital for the reproduction of many plant species and their demise would make it much more difficult for people to grow crops.

Richard Benwell, CEO of Wildlife and Countryside Link, said: “On the day its own advisers warn that the UK is off track to meet environment targets, and highlights farming pollution as a major issue, the Government has granted sugar beet farms the right to use a banned bee-killing pesticide for a fourth year.

“This decision flies in the face of ecological sense. These pesticides are banned for a reason, they are a risk to our wildlife and to human health.

“Industry promised to find replacements, and Government promised better environmental protections. But what we’re getting is delays and yet more broken promises that leave the UK increasingly falling behind on pesticide action.”