A fight over the restaurant inside Bryant Park, the lush, green six-acre patch in the heart of Midtown, is proof positive that real estate in Manhattan is still a hotly contested commodity.

Late last year, Ark Restaurants, which owns the popular Bryant Park Grill, lost a contest to lease the space on the west side of the main branch of the New York Public Library between 42nd and 40th Streets.

In the time-honored tradition of New York tenants, Michael Weinstein, Ark’s chief executive, has refused to leave. The lease expired on April 30, but the Ark staff is still serving jumbo lump crab cakes and Caesar salads to guests.

Mr. Weinstein, who has run the 1,000-seat restaurant for 30 years, contends that the bidding for the lease was rigged for a rival, despite a better offer from his Bryant Park Grill, one of the highest grossing restaurants in the country.

Bryant Park Grill has continued to serve guests, though its lease expired on April 30.

The modestly-priced Grill, Mr. Weinstein argues in a lawsuit filed after he lost the lease, contributed to the transformation of Bryant Park. A haven for drug dealers and muggers in the 1970s and 1980s, the park is now a leafy respite that attracts tourists, secretaries, lawyers and executives alike from the surrounding office towers, an estimated 19 million visitors last year.