A week after talks in Moscow to prepare the way for high-level bargaining this month, U.S. arms control negotiator Paul C. Warnke said yesterday that "the concluding stages have now been reached" in the search for a new strategic arms limitation talks (SALT) treaty, with "a distinct likelihood" of final agreement before the end of the year.

In an address to a State Department-sponsored conference for Philadelphia civic leaders and a press conference, Warnke conveyed an optimistic picture of the chances for a SALT II treaty with the Soviet Union. And he gave more details of some likely provisions than he had made public before.

Limits on the new types of nuclear weapons systems which could be deployed by the two superpowers are the primary issues standing in the way of agreement, according to Warnke.

The likely solution, he said, is for each side to limit itself to one new land-based intercontinental missile system between now and 1985, the termination date of the projected treaty. "I think we can" find a compromise between Soviet and American ideas on these restrictions, he said.

"Technical issues" which remain to be solved include calculation of the range of cruse missles and the problem of defining the kinds of aircraft which can be equipped with long-range, air-launched cruise missiles, he said. Warnke said he expects that some of the technical issues will remain for later resolution by experts, even if Secretary of State Cyrus R. Vance and Soviet Foreign Minister Andrei Gromyko come "close to full agreement" in the talks they have planned for later this month in New York City.

Warnke, accompanied by representatives of other government agencies involved, held two days of talks with Gromyko and lesser negotiators in Moscow a week ago. He said these discussions led to "clarification of positions on both sides" and the elimination of "some misunderstandings."

One of the officials who accompanied Warnke in the Moscow talks was the U.S. ambassador to the Soviet Union, Malcolm Toon. He joined yesterday in the appeal to the 150 Philadelphia leaders on behalf of a SALT II treaty. Toon, who spoke in harsh tones about Soviet internal and international policies, said failure to obtain agreement or ratification of a new treaty would have "a seriously abrasive effect" on Soviet-American relations.

While withholding final judgment on the treaty until all the terms are decided at the negotiating table, Toon said "you can be sure" that President Carter, Vance and Warnke are focused "first and foremost" on protecting U.S. national security. "If I thought that any treaty to be signed with the Soviet Union jeopardized our national security, I would resign my office and then publicly repudiate the treaty," Toon said.

Both Toon and Warnke laid heavy stress on U.S. "national technical means>" a euphemism for spy satellites and other such devices, as the means of verifying Soviet compliance with SALT. Warnke said the "highly sophisticated and highly classified" national systems will permit the United States to know what new weapons the Soviet Union is testing as well as what existing weapons are being destroyed to comply with the quantitative limits to be specified in the new treaty.

Warnke, questioned by reporters, said the alleged transmittal of a top-secret spy satellite manual to the Russians by a former CIA employe was "unfortunate" but did not compromise U.S. inspection systems. He said both the Salt I treaty and agreed clauses of the Salt II treaty prohibit the Russians from trying to conceal their activities from U.S. "national technical means" and from actually interfering with such systems.

The arms negotiator said the Soviet Union has accepted "the complete American position on verification," and in recent months for the first time has supplied detailed data to the United States on the military forces in its arsenal which would be controlled by a new strategic arms agreement. He said there was no major disagreement between the Soviet-supplied data and that which had been reported by U.S. intelligence.

Warnke also said the two sides are in sight of a fereze on number of reentry vehicles, or warheads, which could be placed on each strategic missile. Calling this limitations "very important" because of the dangerous and destabilizing nature of multiple warheads, Warnke said he believes the Soviets will accept a U.S. proposed rule limitimg the number of warheads on any missile system to the maximum number that has been tested on that system so far.