pokesmen for the Port of New York Authority charged yesterday that protection of the Empire State Building's prestige as the world's tallest building was a basic motivation behind an attack made this week by a group of realty men on the proposed World Trade Center.

The authority plans to build the $350 million project on a 16-acre site on the Lower West Side. The world's tallest buildings have been designed for the center — twin towers, 1,350 feet high. The towers will be eight stories, or about 100 feet, higher than the Empire State Building, which has 102 stories, and a 222-foot television antenna mast.

The center's architects, in a statement yesterday, denied that the towers would be unsafe in the event of an explosion or an airplane crash. The realty men had questioned the safety of the project's construction.

Wien Among Opponents

Among the opposing realty group is Lawrence A. Wien, who heads the syndicate that owns the Empire State Building. Mr. Wien also heads syndicate-owners of other large office buildings here — all pre-World War II skyscrapers — at 60 East 42d Street, 200 Fifth Avenue, and four major structures in the garment center.

The Empire State and the other buildings controlled by the Wien interests are typical of the older office buildings that have had to compete with the new glass-fronted skyscrapers built since the war.

The Trade Center, with 10 million square feet of office space, is a new threat to the old buildings. The owners of these buildings fear that the tenants they have tried hard to keep with costly modernization programs will be lured by the glamorous 110-story towers downtown.

Officials of some of the city's largest realty concerns have joined in opposing the center, including Robert V. Tishman, president of the Tishman Realty and Construction Company, Wylie F.L._Tuttle, head of Collins Tuttle & Co., and Walter P. Helmsley, senior vice president and treasurer of Helmsley-Spear, Inc., managing agent of the Empire State Building.

Principal Objections

The group maintains that the project would place 10 million square feet of office space on the market, which, they say, is already glutted with vacant space. The realty men also contend that the Port Authority would gain a tax advantage over private realty interests.

Richard Roth of the architectural firm of Emery Roth & Sons issued the statement defending the safety of the twin towers, which the firm, in association with Minoru Yamasaki, designed for the center.

Mr. Roth said that a structural analysis by the firm of Worthington, Skilling, Helle & Jackson had found that if a tower were hit by an airliner at 600 miles an hour, the damage to the tower would be only local and its occupants outside the immediate area of impact would not be endangered.

The realty group contended that the Port Authority would pay only $3 million in lieu of taxes. A private builder undertaking the project, the realty men said, would be obligated to the extent of $15 million in taxes.

The Port Authority rebutted this charge yesterday, noting that [the?] city had agreed to accept an annual payment of $1.5 million in lieu of taxes. This is the amount the site now yields the city.

The realty group said it would seek to mobilize its campaign against the center with the support of influential organizations like the Commerce and Industry Association, the Citizens Budget Commission, and the Real Estate Board of New York.

Only a spokesman for the Commerce and Industry Association was reached yesterday for comment. He said the association would not take a stand on the campaign, but he noted that some time ago it had made known its approval of the "idea'' of the center.

The project's opponents have the strong support of other respected realty interests.

Robert J. Byrne, head of the Cross & Brown Company, said yesterday that the center would be a catastrophe for the real estate business because of the competition it would bring to the city's old buildings.

A spokesman for the Uris Buildings Corporation, which has built 11.3 million square feet of office space here since the war, said the company supported the opposing realty group.

He said that "building for commerce in New York City is a good thing, no matter who does it, but preferential tax advantages for the proposed Trade Center seem way out of line.''

However, the president of one large concern, Louis Smadbeck of William A. White & Sons, disagrees with the opposition. He said the concept of the Trade Center "is a bit too large,'' but that it was a very forward-looking move.