Wylfa Newydd: 'Lack of detail' in power station plans
The company behind Wylfa Newydd has been told Anglesey council will not support the scheme "at any cost".
When operational, the £10bn nuclear plant is expected to create 850 permanent jobs and should start generating power by 2025.
But in a draft letter, the council has criticised Horizon for the lack of detail in its final consultation.
Horizon said it was "surprised and disappointed" by the council's response.
In the letter, the council's chief executive expressed concern at a decrease in proposed local employment during the building phase.
Dr Gwynne Jones also said there was "an objectionable lack of detail" on proposals to house 4,000 building workers on site.
The letter called for "immediate" investment in education to ensure that local young people will be employed at the proposed power station.
It suggested that, due to the lack of detail, the legality of the process could be in doubt.
"The council remains committed to working with Horizon and other key stakeholders but... not at any cost nor with promises of 'jam tomorrow'," the letter added.
A third and final consultation into the power station plans has been held and Horizon hopes to submit a planning application, known as a development consent order, later this year.
Responding to the council's comment, Horizon's Richard Foxhall said: "They have been made aware of what we intended to consult on before May 2017. They agreed with the content of what we do in the consultation.
Of course, what we've consulted on is what to change since last year, not necessarily on the whole project.
"However we do look forward to working with the council. This isn't the end of the game as far as input."
He added there was no question of the company's consultation process being illegal.