Campaigners fighting plans for a new tip claim the council which will decide whether to allow the application is bombarding them with propaganda promoting it.
Council refuse contractor Onyx wants to build a waste transfer station and material recovery facility in Hollingdean Lane, Brighton.
Members of Dump the Dump say Brighton and Hove City Council have sent out thousands of letters and information about the development - effectively promoting it.
No one was available at the council yesterday to say how much the campaign has cost and where the money was coming from.
The authority and its contractor sent out letters this week carrying the Onyx and city council logo and signed by Jenny Rowlands, the council's director of the environment.
The letter invited residents to a public meeting and answered "frequently asked questions" about the site.
It explained the council's duty to collect and dispose of waste but also emphasised the separate and independent nature of the council's role as a planning authority.
The letter is the second in recent weeks Onyx and the council have jointly sent out.
Dump the Dump campaigners believe it is inappropriate the council is working so closely with Onyx on the proposals as its planning committee will be deciding the future of the plan.
Mother-of-three Mel White, of Hollingbury Road, Brighton, said: "People are asking why they are sending these letters out with both their logos on. How can they be independent?"
Mrs White, whose children drew posters to give to Onyx bosses at Thursday night's meeting, said: "We are in contact with the Government Office for the South-East.
"I presume the council are paying for these letters to go out.
"They came in the Think Inside the Box envelopes which are all about recycling.
"That really angered me because the site is only 30 per cent recycling and the rest is a processing plant."
A spokesman for Brighton and Hove City Council said: "As the authority responsible for waste collection in the city we believe it is essential for the city to have a waste transfer facility.
"We have had a great deal of feedback about the proposal and it is clear a number of people are basing their views on misunderstandings and misinformation.
"We would be failing in our duty if we did not attempt to remedy this.
"The frequently asked questions list gathers facts about what a waste transfer station is, why we believe the city needs one, details about the proposal which are already in the public domain and information about its possible impact on the local environment.
"It is up to the council's planning committee to consider the pros and cons of Onyx's application.
"They have a legal obligation to do so in a fair, open and transparent manner."
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