Paul H. Nitze, a leading opponent of Carter administration negotiating policy in the current strategic arms limitation talks (SALT) with the Soviet Union, yesterday released what he said were new details in the discussions.

Nitze, a SALT negotiator himself from 1969 to 1974 and a former deputy secretary of defense, made the disclosure at a news conference called by the Committee on the Present Danger. The committee on the Present Danger. The committee is a year-old non-profit organization which contends that the Soviet Union may be achieving strategic military superiority over the United States.

Nitze said he was releasing his ananlysis of the SALT negotiations because he feels U.S. acceptance of certain provisions would leave this nation "in deep trouble" in the nuclear weapons balance with the Russians.

His statement, which one administration official said would make the SALT negotiations "more difficult," included the following details:

By Oct. 3, 1980, the United States would limit to 2,160 the number of strategic nuclear launch vehicles - intercontinental ballistic missiles, launchers for submarine launched ballistic missiles plus heavy bombers. The Soviets want a reduction to 2,250 reached by 1982. THe numbers had been mad epublic; the date had not.

The Soviet Union "has indicated willingness to make an informal declaration" - apart from a SALT treaty - "of intentions not to employ the Backfire (a controversial bomber) in an intercontinental role, not to deploy it in a fashion threatening the United States." The Soviets' willingness has been reported; the idea of a declaran had not.

Lower-level SOviet negotiators have insisted that U.S. B-52 bombers be counted in the overall launch vehicle figure or be destroyed, but the question has not been raised among higher-level negotiators.

Soviet negotiators say U.S. FB-111H bombers, which are smaller than B-52s, should be disqualified from carrying cruise missiles; the United States says they should be eligible as long as they are counted as heavy bombers.

The United States wants a three year protocol that would accompany a SALT treaty to expire Oct. 3, 1980, the Soviet Union wants the expiration date to be based on whenever the document is ratified. Both sides seem to be compromising on using the date of signing as the base date.

The administration official, who declined to be identified, said Nitze's release of "great amounts of detail purporting to be negotiating positions cannot make it easier for us to negotiate with the Russians. It can't help but make it more difficult."

Jeremy Stone, director of the Federation of American Scientists, charged that Nitze had issued "a shockingly precise statement of current negotiating difficulties.

"I hope it won't be a forerunner to massive hemorrhaging of negotiating details that would sabotage the SALT treaty," he said. The federation generally favors the U.S. effort on limiting strategic arms.

Nitze said he did not believe the details he released were classified.