The two superpowers held six hours of talks Friday without concluding the deal they want for a reduction in long-range nuclear missiles by about 30 percent.

But they may have improved prospects for success by the end of the year and a summit treaty signing in Moscow in December.Secretary of State James A. Baker III said the outcome depends on a dispute over transfers to allies of nuclear arms and technology that would be banned under the treaty.

He said he made "good progress" on the issue, known as non-circumvention, with Soviet Foreign Minister Eduard A. Shevardnadze. He added that if U.S. and Soviet negotiators in Geneva follow through, two other roadblocks might be cleared.

As a result, Baker said, a U.S.-Soviet treaty to reduce long-range nuclear missiles, bombers and submarines by the end of the yeat "is still very possible."

"We are tired," Shevardnadze said, "but the results are good."

The two other unsettled issues concern the kinds of tests the Soviets would be permitted to conduct of the 154 large SS-18 missiles they would be permitted to keep, and whether the Soviet Backfire bomber would be subject to numerical restrictions.

Apart from their work on strategic nuclear weapons, Baker and Shevandnadze cleared up the few remaining differences on another treaty to reduce North Atlantic Treaty Organization and Warsaw Pact non-nuclear weapons in Europe. Agreement in principle on this treaty was announced Wednesday.

Baker said these issues involved ceilings on aircraft, zones in which arms would be limited and treatment of helicopters.

He provided no details.

Shevardnadze said the result is the Conventional Forces in Europe treaty would be ready to sign at a 34-nation nation summit meeting in Paris Nov. 19-21.

"This is a major accomplishment," Shevardnadze said.