Work is under way on the Newhaven incinerator even though a final legal decision on planning permission has not yet been made.
The controversial project, which is designed to turn rubbish into electricity, has caused outrage among residents who have complained about pollution and health risks.
Opponents are seeking a judicial review of the planning process which led to the scheme being approved.
Today they reacted with anger at news that waste contractor Veolia Environmental Services had begun working at the site.
Liberal Democrat MP Norman Baker, who represents Newhaven, said: "This is absolutely ridiculous. With a judicial review still underway, and the incinerator still requiring a licence, the county council should simply not be proceeding with the construction of the incinerator.
"Given the legal processes still under way, the actions of the county council and Veolia could easily give the impression to a lay person as being in contempt of court."
Last year The Argus revealed the projected cost of the project had doubled to £145.7 million.
Brighton and Hove City Council and East Sussex County Council have spent almost £2 million between them in legal fees to get the scheme off the ground.
For the full story read tomorrow's Argus.