The RSPB and dozens of environmental groups have resigned from the government’s pesticides forum after two decades claiming the use of dangerous chemicals is now far worse than when they joined.

The charity alongside Wildlife and Countryside Link which represents bodies like The Wildlife Trusts and Butterfly Conservation have written to Michael Gove, the environment secretary, warning they can ‘no longer stand by’ while the situation deteriorates.

Two groups, the Pesticides Forum and Voluntary Initiative, were set up by the government in the 1990s to reduce environmental damage from pesticides.

However figures show that since their founding the area of British land treated by pesticides has risen from 45 million hectares to more than 70 million hectares today.

In a letter to Mr Gove, the charities said: “Our organisations have long participated in these voluntary groups in the hope that they would lead to better protection for the environment.

“However, in that time they have failed to take meaningful or significant action to reduce pesticide-related harms.

“Meanwhile the area of UK land being treated with pesticides has risen by more than half, and many of our crops are being treated more times with a wider variety of chemicals.