Rupert Murdoch is reportedly close to negotiating a sale of The New York Post to Manhattan real estate developer Peter Kalikow, according to sources familiar with the negotiations.

Post staff members were told informally yesterday afternoon by Al Ellenberg, the paper's metro editor, that Kalikow's purchase of the newspaper was "a done deal," and that Murdoch would meet with the labor unions Monday to obtain concessions the buyer and seller believe are necessary for the transaction.

If Kalikow purchases the Post for a reported $40 million, he will install as publisher Peter Price, a former bus company executive who is now president of Avenue Inc., the sources said. Avenue is an upscale monthly magazine that is sent to a controlled circulation of well-to-do subscribers in Manhattan.

Because of a Federal Communications Commission rule that forbids one company from owning a television station and newspaper in the same market, Murdoch was required to sell either the New York Post or WNYW-TV (Channel 5) in New York by March 6.

However, Murdoch has filed an appeal on the "cross ownership" question and a federal appeals panel here is scheduled to hear arguments Thursday.

Although the Post has lost millions under Murdoch -- some estimates range up to $17 million last year -- Kalikow reportedly has agreed to keep the paper going for at least three years.

If Murdoch sells the paper to Kalikow, New Yorkers who know the prospective owner said yesterday that they believe he would not change the newspaper's political conservatism.