The United States has agreed to sell jet engines to Yugoslavia for use in a Yugoslav jet fighter currently being developed, Defense Department officials disclosed yesterday.

The move is part of an expanding bilateral military cooperation that will include a substantial increase in U.S. arms sales to Yugoslavia over the next few years.

Defense Secretary Harold Brown and Col. Gen Nikola Ljubicic, the first Yugoslav defense minister to visit the United States, have been discussing military cooperation this week. The visit reflects what officials here call a "very dramatic broadening" of overall bilateral relations since President Tito's visit here last March.

U.S. officials would not specify which jet engine had been offered to the Yugoslavs or disclose details of weaposn procurement. The Yugoslavs' shopping list includes various types of equipment and sophisticated weapons systems and "most of them have been approved," according to a Pentagon spokesman.

It is known the Belgrade was interested in acquiring, among other things, the Harpoon anti-ship tactical guided missile, the air-to-surface Maverick, the anti-tank wire-guided missile Dragon, antisubmarine weapons and an intergrated naval defense system that includes radar and surface-to-air missiles. Also on the list is sophisticated communications gear.

Ljubicic, who arrived here Sunday on a six-day official visit, has met with congressional leaders and senior military officers including Gen. Bernard W. Rogers, acting chairman of the Joint Chiefs of Staff, and Adm. Isaac C. Kidd Jr., commander in chief, Atlantic.

Yesterday, Ljubicic and his party visited the North American Air Defense Command at Peterson Air Force Base in Colorado after spending a day visiting nearby Ft. Carson Army Base. He was later taken to Buffalo, NY., for a tour of Niagara Falls and was scheduled to end his visit in New York City today.

U.S. spokesmen described the talks between Brown and Ljubicic as "very warm and cordial." The Yugoslav minister, who has held his job for more than 10 years, is one of the key figures in Yugoslavia and is likely to play a pivotal role after President Tito, 86, leaves the political scene.

Yogoslavia is the only Communist country to receive U.S. military assistance. Following Tito's break with the Russians in 1948, the Yugoslava received more than $1.7 billion in U.S. purchases of U.S. arms. In 1961 Tito refused to extend the U.S. Yugoslav military cooperation pact. In recent years the Yugoslavs again have become dependent on the Soviet Union for procurement of sophisticated arms.

The decision to resume military cooperation, which was taken two years ago and is now being implemented, reflects Belgrade's desire to diversify the sources of weapons supplies and reduce dependence on the Russians. In turn, Washington is interested in strengthening the Yugoslav military as a means of ensuring Yugoslavia's independence.

Officials were reluctant to discuss details, but they said they expected U.S. arms sales to Yugoslavia to expand to "several millione of dollars annually."

Brown visited Yugoslavia last October, the first U.S. defense secretary to go to a Communist country.