In the flyer, entitled "Gypsy and Traveller site coming to your area soon!", the Conservative MP attacked the local Labour council for a lack of consultation on its plans and asked residents of his Monmouthshire constituency: "Would you like to see a Traveller site next to your house?"

The Travelling Ahead Advocacy and Advice Service, which provides support to Gypsy, Roma and Traveller communities across Wales, posted the leaflet online, calling it "unacceptable", and said they had made complaints about it to his party, the Equality Commission and the police.

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Trudy Aspinwall, a project manager with the organisation, told Wales Online it was a "disproportionate and hostile response targeted at the race and ethnicity" of the community, which would "make them feel like they are not wanted anywhere".

But in a statement, Mr Davies denied it was discriminatory, saying the proposed sites were "a legitimate matter for public debate and scrutiny", and it was "entirely valid to criticise a lack of wide public consultation by a council".

He added: "I have been contacted by many upset residents at the shortness of the consultation and the proposed locations for the sites.

"I have also been told that many from the gypsy and traveller community are also upset at the proposed locations for the sites. This is not a criticism of the gypsy and traveller community."

Gwent Police confirmed to Sky News they were aware of the flyer, with Detective Inspector Steve Thomas adding: "Officers are reviewing the content of the leaflet and its impact on the gypsy and traveller and settled communities in Monmouthshire.

"We take any allegation of discrimination extremely seriously and we're committed to ensuring our communities are safe places and welcoming for all."

But a source close to Home Secretary Suella Braverman said the investigation "appears to be a waste of time", adding: "The police should be laser-focused on further cutting crime and not investigating legitimate public concern.

"The public want to see police out on their streets preventing crime and catching criminals, not inspecting MPs' leaflets."

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Deputy Prime Minister Oliver Dowden rejected claims the leaflet was racist, telling Sky News: "I think that what David Davies was doing was highlighting the failure of the local Labour council to carry out a proper consultation on this. That is entirely what people would expect their local members of Parliament to do.

"He's standing up for his constituents, making their case for them and I totally support his right to do that."

Shadow business secretary Jonathan Reynolds said he hadn't seen the leaflet, but warned about the importance of language when dealing with such sensitive issues.

He told Sky News: "There's a way to ask legitimate questions of your electorate and engage with them in a way which is seeking their views, and there's a time when sometimes people use language, I think, to not really engage constituents, but to try and, you know, cause alarm, cause fear and frankly use it for their own political ends.

"These are difficult issues at times. Are they doing it sensitively? Are they doing in good faith? If they're not, they should be criticised. If they're are, I'll give them some leeway."

Sky News has contacted Mr Davies for a comment.