Nabisco Brands Inc., the giant New Jersey-based company best known for Oreo cookies, Saltine crackers, and Planter's peanuts, said yesterday it has held "exploratory talks" about a merger with R. J. Reynolds Industries Inc., the North Carolina tobacco and consumer products company.

Trading was halted in Nabisco stock late in the day after Wall Street rumors began to spread that Reynolds plans to offer $90 a share, or about $5.2 billion, for Nabisco. After trading was halted, Nabisco acknowledged that it has held discussions with Reynolds and "has reached no conclusion." Reynolds officials declined to elaborate on the statement.

Nabisco stock jumped 3 1/8 yesterday to close at 71 3/8 with 549,300 shares changing hands.

Analysts said the acquisition would help Reynolds in its quest to expand its consumer products division. Reynolds consumer products include Del Monte fruits and vegetables, Smirnoff Vodka, Hawaiian Punch and Kentucky Fried Chicken.

"The speculation I have heard is that Reynolds is considering bids up to $90 a share," said Merrill Lynch analyst William Maguire. "It makes sense for Reynolds to seek a $6 billion food company to augment its Del Monte unit and give it more shelf space and power in the supermarket. But I think it should be valued less, perhaps in the $80-a-share area. Any price between $80 and $90 a share is a good price as far as Nabisco is concerned and one at which they would probably sell out."

Duff & Phelps analyst John Bierbusse said he thought the rumored $90-a-share price was reasonable. He said a merger would give Reynolds access to new markets such as Canada, where Nabisco is the largest food company. He said Nabisco, which acquired Standard Brands in a 1981 merger, also would give Reynolds the ability to develop and bring new products to the market quickly.

In a cover story this week, Business Week magazine called the Nabisco-Standard Brands merger of 1981 a "corporate marriage that seems to be working." Business Week said that transaction is "one of the few clearly successful corporate mergers. A key reason is that the $2 billion marriage of the two food giants was a true merger of equals. Its intent: to exploit each corporation's geographic, distribution, technolgical and management resources in order to produce a more competitive force in the food industry."

Nabisco had revenue and net income of $6.3 billion and $309 million last year, while Reynolds had revenue of $9.9 billion and net income of $843 million.

"I think it a combination would make a very exciting consumer products company," Bierbusse said. "It would generate a company with an awesome presence in the grocery store, as you combine two companies with very strong balance sheets and secure market shares in their products, for the most part."

Mergers have been a popular way for food companies to expand, with increased distribution the most frequently offered reason for multibillion-dollar mergers such as the recent combination of Beatrice Cos. and Esmark Inc. Beatrice said at the time that acquiring Esmark would enable it to take several popular regional brands to the national market.

Other popular Nabisco products include Life Savers, Butterfinger and Baby Ruth candy bars, Carefree chewing gum and Blue Bonnet margarine.

Reynolds' tobacco products include Winston, Salem, Now, Camel and Vantage cigarettes. In addition to Smirnoff Vodka, Reynolds owns Harvey's Bristol Cream Sherry and Lancer's wine.