The pair of major landlords waging a campaign against the Freedom Tower have been arguing publicly against the project without disclosing that they personally could lose millions of dollars a year if it is built.

Last week, developers Douglas Durst and Anthony Malkin put their names at the bottom of full-page advertisements in several New York City newspapers by a group they are co-chairmen of called The Continuing Committee for a Reasonable World Trade Center. The advertisements said the project was ill conceived, too expensive, and poorly planned.

The ads were released just after the Spitzer administration indicated it would move forward with the project, and before the Port Authority approved several key construction contacts. They went into detail about the tower’s architecture, its security vulnerabilities, its rent roll, its height, its name — just about everything except for the fact that the project includes plans for television and radio broadcast antennae that would replace those on the old twin towers, and compete with those on buildings owned by Messrs. Malkin and Durst.

Mr. Malkin controls the Empire State Building and Mr. Durst owns the Condé Nast Building at 4 Times Square, both of which are now the most desirable locations in the city for the location of television and radio broadcast facilities and their antennae.

Following the destruction of the World Trade Center, the Empire State Building antenna, at about 1,454 feet tall, became the primary antenna for the area’s major television stations. The Conde Nast building antenna, at about 1,141 feet tall, became a favorite backup.

The Port Authority, which owns the Freedom Tower, is currently in negotiations with the Metropolitan TV Alliance, a conglomerate of local television broadcasters. The MTVA has committed to using the proposed 256-foot broadcast antenna on top of the Freedom Tower. Sources close to the negotiations say the contract is nearly complete and would net about $10 million a year in annual rent to the Port Authority. A 20 to 30 year contact worth hundreds of millions of dollars would contribute to the financial viability of the Freedom Tower, they say.

A source close to the negotiations between the Port Authority and the MTVA said the new antenna, reaching higher than all competing antenna facilities, at 1,776 feet tall, would be the highest point in the region, offering broadcasters the clearest level of service. Other antennae, like the facilities on Messrs. Durst or Malkin’s buildings, could still be used to create a signal redundancy, but would probably command lower rents.

In a telephone interview, Mr. Malkin said he does not view the Freedom Tower’s antenna as a “competitive threat.” He said his public involvement is not financially motivated.

“Whatever revenues we have are locked in. They are long-term contracts. I will likely be retired or retiring before it become an issue,” Mr. Malkin said. “When the World Trade Center was in place and functioning, our broadcast facility was full. If we are not the number one facility, we are the number two. Broadcasters will have to use our facility.”

A former top real estate official at the Port Authority who negotiated the last deal between broadcasters and the former World Trade Center, James Connors, now works for Mr. Malkin.

A spokesman for the Durst Organization, Jordan Barowitz, said that antenna revenue was not behind Mr. Durst’s public campaign. He said Mr. Durst would like to see the Freedom Tower rebuilt, but redesigned and delayed. Mr. Barowitz said revenue from antennae accounts for less than .5% of the Durst Organization’s total revenue.

Both Messrs. Durst and Malkin have said they were continuing a family tradition. In the 1960s, Mr. Durst’s father, Seymour Durst, and Mr. Malkin’s grandfather, Lawrence Wien, formed the Committee for a Reasonable World Trade Center to protest the original twin towers.

A spokesman for the Port Authority, John McCarthy, declined to comment because the antenna agreement is being negotiated.

A spokesman for the MTVA, Pat Smith, would not comment on the status of the negotiations, but he said new antenna facilities are necessary. He said the broadcasters are committed to a Freedom Tower facility.

“There are still millions of people in the metropolitan area who do not have cable, or who have additional televisions in the house without cable. They are not getting a fully adequate signal. It would also facilitate the transition to digital television,” Mr. Smith said.

Before committing to the Freedom Tower antenna, MTVA had considered other sites in New York and New Jersey, including the possibility of a free-standing antenna not connected to any existing building.