Opponents of the King Alfred redevelopment at Hove have asked the Government to intervene and stop the scheme.
The £290 million housing and leisure complex for Hove seafront was approved by Brighton and Hove City Council on Friday.
It was passed on the narrowest of margins with the casting vote by Labour councillor Les Hamilton, chairman of the planning sub-committee.
The decision is one of the most momentous ever in Brighton and Hove and will pave the way for 750 new homes, hundreds of jobs and £80 million of community benefits.
Labour backed the massive redevelopment and council leader Simon Burgess described its approval as "such good news for the future of the city".
Supporters say it would open the way for the city to become a worldclass architectural hub and attract huge investment.
All five Conservative councillors on the committee were against the plans, calling them a "monstrosity". The party has written to the Government Office for the South East asking it to call in the decision.
Conservative leader Brian Oxley, who represents Westbourne, said: "There are a lot of disappointed and very angry people in our area.
"They just can't believe the planning committee approved this.
"There's a lot of concern not just about when it's built, which will take at least five or six years if it happens, but what will happen to the present King Alfred in the meantime."
GOSE represents Secretary of State Ruth Kelly on planning matters in Sussex.
It can call in decisions made by local authorities for closer scrutiny and investigation.
Coun Oxley said the city council's decision needed to be reviewed because it was so controversial and would have a major impact on the appearance of the area.
He said there were concerns about the towers, designed by Frank Gehry, being a terrorist target.
Coun Oxley said: "When the i360 project was being looked at the police said there was the potential for it to be a target and we think there could be a national security issue with the Gehry towers because they are even taller than the i360."
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