'Maximum pressure' needs to be put on the Government to deliver the new Kingston Academy, according to a leading councillor.
New Kingston Council leader Kevin Davis said he was "increasingly concerned" at a lack of information from the Department for Education (DfE) and Education Funding Agency (EFA) with just 15 months to go.
The opening of the school has already been pushed back by a year, from 2014 to 2015. The planning application has still not been approved.
He said: "Although the local authority is obviously a part of the school, the future of how it arrives is completely out of our hands."
Coun Andrea Craig, lead member for children, youth and adult learning, said: "We're at a point where we have to put maximum pressure on the DfE and the EFA, who are in charge of delivering the school.
"It can happen, and everyone wants to make sure it does happen."
But Sophie Cavanagh, appointed principal of Kingston Academy in March, said it would be "100 per cent ready" by September 2015.
She said: "Behind the scenes there is a massive amount of work being done. Rest assured it is on target."
A DfE spokesman said: "The Kingston Academy is on track to open in September 2015 as planned.
"A principal has been appointed and the North Kingston Centre site has been secured.
"Work will start soon, leaving plenty of time for it to open in September 2015."