The architect with the winning design to rebuild the World Trade Centre site is embroiled in an increasingly bitter dispute with the property developer who owns a lease on the site, as artistic vision clashes with the commercial demands of prime real estate.

The architect, Daniel Libeskind, yesterday met the property magnate, Larry Silverstein, to iron out apparently intractable differences over what will actually be built on Ground Zero. Mr Libeskind's design, which was chosen from a shortlist of nine, includes a sunken space that will be left under the building as a memorial, and a 1,776ft (540-metre) tower which would be the world's tallest building, topped by six enclosed botanic gardens.

However, the site was leased by Mr Silverstein two months before the attacks, and Mr Silverstein, who received $1.3bn (£814m) in insurance from the buildings and may yet receive between $3.5bn and $7bn extra, wants more office space. He has also questioned whether businesses will rent space next to a hole that reminds them of their vulnerability.

According to the New York Times, Mr Libeskind believes he has a public mandate for his design; Mr Silverstein feels that as the man who has to rent the property his should be the final say. When Mr Libeskind's design was announced in February as the winner the New York governor George Pataki hailed it as "truly an emotional protection of the site of Ground Zero itself ".

The mayor, Michael Bloomberg, called it a plan that would restore Lower Manhattan "to its rightful place in the world" . But the feuding over both the moral and legal ownership of the land started almost immediately. It was made clear that Mr Libeskind's plan would serve only as a guide to the final design, while a source close to Mr Silverstein said: "The developer will decide everything about the design."

Meanwhile, survivors' groups grew concerned that any adaptations might relegate the importance of the memorial and, particularly that a bus terminal could be built on the land where most of the human remains are. Responsibility for the site is divided between the governors of the states of New York and New Jersey, who own the land through the Port Authority, and Mr Silverstein, who leased it from them.

Mr Bloomberg, local residents and the survivors' groups have no statutory rights in the decision making process, although the latter could hold some political and moral clout. Representatives from both the Port Authority and the Lower Manhattan Development Corporation, which was set up to oversee the reconstruction work, were also likely to attend the meeting.

The wrangling has become more intense as Mr Pataki's deadline for building to start by the summer of 2004 approaches. The pressure of time has strengthened Mr Silverstein's hand, not least since his suggested changes would make the building more straightforward to build. Mr Silverstein has hired one of Mr Libeskind's rivals in the design competition to help him come up with plans.

Mr Libeskind has hired a lawyer to protect his interests. At the heart of the row stand the huge towers that took centre stage in the original design. Mr Libeskind's plan was to provide an imposing replacement for Manhattan's skyline. Mr Silverstein believes that, as proposed, the towers will not offer the right office space to attract the tenants he wants and will cost too much to build.

As the dispute has dragged on Mr Pataki's office has become increasingly impatient. "This process leaves for error or delay, for parochial concerns of unnecessary battles," a spokeswoman the New York Times. simply you're either part team or you're not." Mr Libeskind tried down the row.

"Of course have to stick up integrity of our plan. compromise so the evolves into something really workable. But same time we must keep boundaries where we negotiate."