A new residential tower being considered for 1 Madison Ave. could become the city’s tallest apartment building.

We’ve learned that Elad Properties, which is redeveloping the Plaza Hotel and residences, has an agreement with SL Green Realty Corp. to use SLG’s more than 400,000 feet of air rights to construct a 74-story tower on top of the 1.2 million-foot, 14-story building in which investment bank Credit Suisse both has an interest and its offices. Daniel Liebeskind is the architect.

But don’t get Elad’s development plans confused with the 41-story adjacent building to its north. Though that tower, which is better known as the landmarked Clock Tower, once had the address 1 Madison Ave., it was renamed 5 Madison Ave. after it was sold to Africa-Israel for $200 million, with plans to develop the site into residential units.

We’re sure right now that Africa-Israel’s Lev Leviev is steaming that his rival, Yitzhak Tshuva, and Tshuva’s local boss, Micki Naftali, will be dwarfing his own scheme.

The two buildings, together known as the Met Life Building, comprise 1.93 acres and take up the entire block bounded by 23rd and 24th streets and Madison and Park Avenue South, but the Clock Tower itself takes up just the corner of Madison and 24th Street.

Israeli press reports said that Elad would spend $450 million to create the new 900-foot-tall building overlooking Madison Square Park.

Elad issued a statement clarifying other erroneous reports that claimed city approvals were in place. “Any discussion of a potential development at 1 Madison Avenue is highly premature. It is in its earliest concept phase and no decisions have been made about any aspect of the potential development,” the company said in its statement.

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The BBC is taking over the space at 251 Park Avenue South that was once occupied by cable channel FX, which like The Post is owned by News Corp. The 7,000-foot space came with its own TV studio. The five-year deal had an asking rent of $55 a foot.

Daniel Lipton and Peter Pacific of the Kaufman Organization represented the tenant, while Frank K. Ring of FM Ring Associates worked for the owners.

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A juicy piece just got squared in the Meatpacking District.

Two small buildings at 414-16 W. 14th St. and 418 W. 14th St. were just purchased last Friday by Sitt Asset and The Carlyle Group for an area record of $2,500 a foot, or $70 million.

The sellers were the Icon Group’s Todd Cohen, Terrence Lowenberg and Michael Miller, who bought the buildings from an old-time meatpacking family for $18.5 million in March 2006. The SittsBarry and sons Eddie, Ralph, David and Jack – were brought to the building by Christopher Owles of Sinvin Realty and made an unsolicited offer.

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The northwest corner of 46th Street and Eighth Avenue was just sold to TriBeach Holdings in three deals over two years totaling $80 million.

The Scheiner family originally owned the buildings together with the Bernard Rose Trust. About two years ago, the Trust sold its 20 percent interest to TriBeach for $15 million and that firm has now bought the additional 80 percent from the Scheiners for $61.5 million.

The properties include 733-39, 741-43 and 763 Eighth Ave. and 303-05 and 307-11 W. 46th St. Another 14,700 feet in air rights above 765 Eighth Ave. were just purchased for $3.5 million or $250 per foot from another seller.

TriBeach intends to construct a hotel with ground-floor retail that may also include condos on top.

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