Landmark legally binding targets to clean up Britain’s waters and to boost the abundance of wild species are being delayed, the Environment Secretary has admitted.

Therese Coffey said the Government would miss Monday’s deadline to publish its targets under its obligations under the post-Brexit Environment Act.

Conservative peer Lord Lucas accused the RSPB of being “lying turds” as the charity raised concerns.

The row came as Rishi Sunak was criticised for a “failure of leadership” after he pulled out of attending the Cop27 climate summit in Egypt next month.

Ministers had set the October 31 deadline for publishing targets for air quality, water, wildlife, waste reduction and resource efficiency.

But Ms Coffey told MPs in a written ministerial statement that it will be delayed as 180,000 responses to its consultation need to be “analysed and carefully considered”.

“In light of the volume of material and the significant public response we will not be able to publish targets by October 31, as required by the Act,” she said.

“However, I would like to reassure this House and all interested parties that we will continue to work at pace in order to lay draft statutory instruments as soon as practicable.”

Using the hashtag “AttackOnNature”, RSPB England shared a video on Twitter of Green MP Caroline Lucas asking the Prime Minister about Liz Truss’s government having taken a “wrecking ball to nature”.

Lord Lucas responded: “You lying turds. There is no attack on nature, there never was an attack on nature, and that is what Rishi confirms.

“You used to be, and could be again, a source of valued and truthful advice. But not while you are hooked on this outrageous lie.”

Mr Sunak spoke of his pride in the Commons of the “landmark” Environment Act, adding: “We will deliver on all those ambitions”.

Katie-Jo Luxton, the RSPB’s director for conservation, said: “It is deeply concerning that Defra has failed to meet the deadline to set the legally-binding targets that were promised in the Environment Act.

“Nor have they given a clear indication of a new deadline, leaving a huge question mark over when we can expect to see the final targets.

“Meaningful and ambitious targets should be a catalyst for action for the next decade and beyond, and a reassurance for the public, who are rightly concerned that almost half of England’s wildlife is in decline and more than one in ten species is threatened with extinction.”

Labour shadow environment secretary Jim McMahon said: “The Government’s admission that it will not be meeting the deadline for its Environmental Act targets is a huge embarrassment to them and deeply worrying for the UK’s environment.

“Failing to meet the legal deadline to introduce targets to ensure we have clean air land and water amounts to a monumental dereliction of duty.”