Nutrient neutrality rules were designed to prevent the environment being polluted by materials produced in new building projects.
The charity, which received more than £10 million in UK Government grants last year, also pointed to environmental pledges made in the 2019 Tory manifesto and in the trio’s speeches.
But on Wednesday night, the charity was condemned for “dishonest party-political activism”.
A senior Tory source told The Telegraph: “It’s really disappointing to see a once-great charity resort to hyper aggressive and dishonest party-political activism. People who donate to the RSPB don’t expect to see their money spent in this way and it raises serious questions for the trustees and the regulator.
“Sadly, this is an increasing trend amongst some mega-charities who are increasingly giving the sector a bad reputation by trying to compete for media coverage with extremist groups like Extinction Rebellion and Just Stop Oil.”
The RSPB has become increasingly outspoken about ministers’ environmental records, with its chief executive Beccy Speight last year decrying their “attack on nature”.
It has joined forces with others including National Trust, Wildlife and Countryside Link, and the Wildlife Trusts to fight policies they say will threaten protected habitats and species.
A government spokesman said: “We’ve always been clear we will never compromise our high standards and we are fully committed to our ambitious and legally binding commitments on the environment.
“The reforms we’ve set out will see us tackle pollution at source in a way that these legacy laws never addressed through a significant package to restore waterways and leave our environment in a better state than we found it.
“This will see us more than offset the negligible impact of new homes on levels of nutrients, by doubling the investment for Natural England to tackle nutrients, bringing this to £280 million, drawing up bespoke plans to restore nature in the most affected areas, and providing more support than ever to help farmers reduce pollution from essential agriculture.”