The prime minister has been accused of inventing an allegation that wildlife rules are holding back house-building.
In his recent speech on job creation, Boris Johnson said: “Newt-counting delays are a massive drag on the prosperity of this country.”
But environmental groups say the allegation is a political trick with no basis in fact.
And BBC News has been unable to find evidence that wildlife surveys are unduly delaying development.
Downing Street passed our inquiry to the environment department Defra, which has not offered evidence. Nor has Natural England, which is responsible for wildlife protection.
The Local Government Association said it was not aware of any evidence that newt surveys were unnecessarily holding back projects.
And the Home Builders Federation said it has many concerns over planning, but newt surveys were at the bottom of the list.
“The PM’s speech was pure fiction,” Craig Bennett, head of the Wildlife Trusts, which runs conservation projects and education projects, told the BBC.
“It may sound funny referring to newts, but actually it was rather sinister. In the environment movement we know referring to newts is a dog whistle to people on the right of his party who want environmental protections watered down.”
There have been complaints about newt-related delays in the past, but the authorities have moved to speed permits for new developments.
Historically, would-be developers would have to wait for a survey to check whether their plans might disturb great crested newts, which are uncommon in Europe.
Now technology is taking over. Natural England, is using a method in which samples of pond water are taken and analysed to detect fragments of newt DNA.
The process is so fast that the organisation is often able to carry out research in advance so developers can get instant information.
A springer spaniel called Freya is also playing a part. She works for Wessex Water, sniffing out newts in ponds. The firm says that, thanks to Freya, it can conclude its surveys in days, not weeks.
What’s more, if great crested newts are discovered, that doesn’t sterilise development on the site.
Under recent rules, the developer can proceed so long as they provide alternative sites in a way that leaves nature better off than before.
Newt rules have been under attack in the past from politicians complaining that the UK has “gold-plated” EU regulations.
But a government review in 2012 said: “The directives are working well, allowing both development of key infrastructure and ensuring that a high level of environmental protections is maintained.”
The head of Natural England, Tony Juniper, told the BBC: “We have to find the best ways of pulling together our environmental ambition at the same time as the economic one. These two things have to be pursued together, not traded off against each other.”
Green groups furious with Mr Johnson are meeting Environment Secretary George Eustice next week to express their concerns about his speech.
I understand he is uncomfortable about the PM’s apparently evidence-free reference to newts