August 26, 1983

After months of detente, the cold war between Glen Cove, L.I., and the Soviet Union heated up again yesterday. The Justice Department filed suit in Federal District Court in Brooklyn, seeking to force Glen Cove to open its beaches and tennis courts free of charge to Soviet diplomats who live on a 36-acre estate there. The dispute had been limited to angry exchanges of letters and telephone calls. The last skirmish occurred in the spring, when Mayor Alan M. Parente rejected a State Department proposal that called for the Russians to pay $4,800 to swim and play tennis and golf at municipal facilities.

Three of the nation's leading steelmakers yesterday announced increases of about 7 percent in the price of sheet and strip steel products that are used by the automobile industry and in consumer goods. The three - the United States Steel Corporation, the industry leader; No. 2 Bethlehem Steel, and the fifth- ranked Republic Steel Corporation - said the increases would take effect Sept. 1. Other producers said they were studying the action. The increase will raise the list price of cold-rolled sheet steel to $563 a ton, and zinc-coated galvanized steel to $606 a ton.

Savings banks in New York State showed considerable improvement in the second quarter, although more than half of them continued to report operating losses, according to the state banking department. Operating losses were cut dramatically, to a total of $55.1 million, from $269.9 million in the second quarter of 1982, and from $116 million in the first quarter of this year. As a result, the sense of impending doom within the industry has lifted. It has become far less likely that Federal and state regulatory authorities will force mergers of failing institutions into stronger ones.

President Francois Mitterrand said today that French troops had been sent to Chad to ''bring peace,'' but he warned that, if threatened by Libyan-backed rebels, they could go on the offensive. The President's statements, his first full exposition of policy since fighting flared in the Central African nation two months ago, appeared as a question- and-answer interview in Le Monde. The questions were not submitted in advance, but the text was personally reviewed by the President before its publication this afternoon. The interview came amid a growing public debate over France's military buildup in Chad. It also came as Paris pressed a diplomatic effort designed to avoid a clash with Libya. The commitment by France is rapidly becoming larger than any in Africa since the Algerian war two decades ago.

Burlington Northern Inc., which acquired 48 percent of the stock of the El Paso Company through a tender offer in January, yesterday offered to acquire the remaining 52 percent of the Houston-based energy concern in an exchange of cash and stock valued at $670 million. Burlington said it was offering $12 in cash, as well as newly issued preferred shares, for each of the 28 million El Paso shares it does not now own, an exchange valued at $24 a share for the El Paso stock. The railroad company's earlier acquisition of El Paso stock was also valued at $24 a share, but was paid entirely in cash.