A battle is looming on the East Side as a developer is set to begin the formal approval process for his proposal to construct six large residential towers, one office tower, and 1,550 public parking spaces just south of the United Nations headquarters. Real estate analysts said the ambitious development plans could transform Manhattan’s Midtown East area into an international community of diplomats.

On August 20, the Department of City Planning is expected to certify a development proposal by Sheldon Solow that would rezone a nine-acre industrial site along East River between 35th and 41st streets, formerly used by Con Edison, for residential and commercial development.

Mr. Solow’s proposal includes six residential buildings between 37 and 69 stories high, as well as a 666-foot-tall commercial tower. Currently, the iconic 505-foot Secretariat of the United Nations complex is the tallest building in the area. The new development is expected to attract up to 10,000 new residents and 5,000 office workers.

According to City Council Member Daniel Garodnick, who represents the neighborhood, Mr. Solow’s proposed rezoning “would allow buildings that are too big, too dense, and could include a commercial office building that does not belong there.” Alongside Mr. Solow’s proposal, the city planning department will also consider an alternative plan submitted by the community, which seeks to minimize the size of the proposed parking garages, open up access to the waterfront, and add affordable housing units and a public school to the mix.

The state senator who represents the neighborhood, Liz Krueger, said she thought the school “was one thing the developer had committed to verbally, but we don’t see any reference to space for schools in his plans.”

Mr. Solow is also encountering strong opposition to his proposed public parking garages in a climate in which the city has expressed interest in boosting mass transit and removing vehicles from congested streets. The large garages could attract commuters entering the city from the FDR Drive and encourage more drivers to enter the city, transit experts said.

“His plan seems counterintuitive to the mayor’s congestion pricing plans and the city’s overall desire to decrease the volume of cars” in Manhattan, Ms. Krueger said.

A spokesman for Mr. Solow declined to comment for this story. Real estate analysts, meanwhile, said the development would be more lucrative if it included more office space, and perhaps even a hotel.

“Mr. Solow has the ability to create his own environment there — it’s almost like a suburban town,” a managing director of Real Capital Analytics, Daniel Fasulo, said. Diplomats and international clients conducting business with the U.N. would be attracted to the location, Mr. Fasulo said, and wealthy medical professionals who work at nearby hospitals could also be interested in the condominiums.

Condominiums in the neighborhood now fetch about $1,500 a square foot, and analysts said new condominiums with waterfront views could sell for far more.

Mr. Solow, who is known as an “as of right” developer — that is, one with little experience in the seven-month-long public review process needed to rezone a site — purchased the Con Edison site in 2004 for $630 million.

“The greatest public interest is not creating impenetrable wall between the city and the river,” the president of the Municipal Art Society, Kent Barwick, said. In the past, the United Nations has cited security concerns in closing the waterfront to the public, but has recently shown a new willingness to open up access there, Mr. Barwick said.