The new City & West End Developments scheme is competing with a Prudential plan to develop the 1.8 ha site.
Commission chairman Lord St John of Fawsley responded to the City & West End plan in a letter to Westminster City Council.
He said he welcomed the comprehensive approach taken by City & West End, but outlined a number of reservations that he had about the scheme, which is designed by Hamilton Associates.
The letter said: "As far as the masterplan is concerned, the commission believes that it fails to acknowledge the richness of the site or create a proper sense of the grain of the city. The gesture of the curved range of offices has not generated interesting spaces." Other objections include the proposed open space, the quality of the replacement for the Normandie Hotel and plans for a central office block tower.
The Prudential plan was rebuked by Lord Fawsley last March. The RFAC will consider a revised scheme from Prudential next week.
