PHILADELPHIA Fearful that demolition is already underway at the historic Boyd Theater, officials at the Preservation Alliance for Greater Philadelphia said they would seek a court order Tuesday to stop the owner from proceeding with plans leading to a new multiplex.

Workmen were seen moving heavy machinery into the Boyd's ornate auditorium on Monday morning, leading preservationists to conclude that the theater's owner, Live Nation, had begun gutting Center City's last art deco movie palace, said Caroline E. Boyce, the alliance's director.

Ben Leech, the group's advocacy director, said he could hear hammering when he walked past the theater's exit doors on Sansom Street. Several other people also reported seeing workmen going in and out. A demolition permit was posted on the theater's Chestnut Street facade over the weekend.

"I can't think of what else they'd be doing other than demolition," Leech said.

On Friday, the Historical Commission granted Live Nation permission to raze the historically designated theater at 1910 Chestnut St. on the grounds that the building had become a financial hardship. The company, which is required to retain the Chestnut Street entrance, intends to sell the building to a Philadelphia developer to erect an eight-screen multiplex for the Florida entertainment company iPic.

The Preservation Alliance and the Friends of the Boyd plan to appeal the decision.

Although the 1928 movie palace is a landmark, only the exterior is protected under city law. The Boyd's interior, with its etched-glass lobby and gilded and multicolored auditorium, is equally prized by preservationists.

Live Nation said it sought the hardship ruling because iPic needs to demolish the outer walls to construct its new screening rooms. The demolition permit was issued Feb. 25, but not posted until Saturday.

Live Nation's point person on the Boyd, executive James Tucker, could not be reached for comment on Monday.

The company's local attorney, Matt McClure, and developer Neil Rodin did not return phone calls.

The Nutter administration is unlikely to halt the demolition. During the lengthy debate over Live Nation's hardship request, it did not take sides in the case, even after a donor stepped in at the eleventh hour and offered to buy the theater.

"We've let the process run its natural course, and I don't intend to intervene," said Alan Greenberger, deputy mayor for commerce and planning. "The process has determined there is hardship. There are legal permits in place, and that's OK."

"We didn't want to see this building sit around for another 10 years," Greenberger added. The theater closed in 2002.

The donor, who has insisted on remaining anonymous, had offered to take the building off Live Nation's hands for the same price iPic offered, $4.5 million. Additional funds would have to be raised to convert the building into a multipurpose cultural venue.

Friends of the Boyd president Howard Haas, who has fought for more than a decade to save the movie palace, said he was outraged that Live Nation began demolition so quickly, before the group could appeal the hardship ruling.

"This certainly takes away from the fundamental due process," he complained. Since iPic must demolish the theater walls to build its screening rooms, he argued that "this gutting serves no purpose other than to stop us from taking the appeal."

Leech said he was concerned that the Historical Commission did not impose any restrictive conditions when it approved the hardship sale. In most cases, developers are required to show proof of financing before they are allowed to proceed with demolition.

"It's all legal, and it's all disgusting," he said.