Soviet leader Mikhail Gorbachev, in a report today to Communist Party leaders, said that a new summit meeting with President Reagan was possible, but only if the atmosphere was conducive to "real agreements."

"We are not slamming shut the door," Gorbachev said, according to the Soviet news agency Tass. But he questioned recent U.S. actions, including renunciation of the unratified SALT II treaty, which he said "still further aggravates international relations."

"Do they in Washington really want a new meeting," Gorbachev asked, "or is talk about it simply an attempt to delude the world public opinion?"

In his report, Gorbachev also elucidated some of the points in a Soviet arms control package put forth last week at the U.S.-Soviet talks in Geneva.

He proposed that both sides "agree on nonwithdrawal" from the 1972 Antiballistic Missile Treaty "in the course of at least 15 years, and limit the SDI-related research to the level of laboratory tests," Tass said.

Previously Gorbachev, in discussing the U.S. space-based Strategic Defense Initiative had said only that "fundamental research" could be allowed. His statement today is the first formal Soviet offer to permit laboratory testing of SDI-related systems under an arms control agreement but it is unclear whether that language is in the proposal presented in Geneva.

Gorbachev called for the two sides to limit their strategic nuclear weapons to 1,600 units -- meaning strategic delivery vehicles, including ballistic missiles, bombers and long-range cruise missiles -- and their nuclear warheads to 8,000, Tass said.

At the Geneva summit talks last November, Gorbachev and Reagan had agreed to seek a 50 percent reduction in nuclear warheads to bring existing arsenals down to 6,000. The latest Soviet proposal would thus represent a less-dramatic cut of one-third.

"The question of medium-range weapons capable of reaching the territory of the other side, including that of long-range cruise missiles, could be solved separately," he said.

Overall, Gorbachev said the Soviet Union has made "new steps facilitating the search for mutually acceptable accords" at the Geneva negotiations.

"If the American side ignores this time as well our initiatives, it will become clear that the present U.S. administration is playing an unseemly game in the most serious question on which is determined the future of mankind," Tass quoted Gorbachev as saying.

Gorbachev said the "world is alarmed by the American behavior" in refusing to join in a Soviet moratorium on nuclear testing, now extended until August. He said the need for a test ban had been reinforced by the experience of the Chernobyl nuclear accident.

The State Department said it had no comment tonight on Gorbachev's speech.

Gorbachev's report was to the newly selected Central Committee, which met today before a regular session of the Supreme Soviet, the national legislative assembly, on Wednesday. The Supreme Soviet will adopt a draft of the 1986-1990 five-year plan.

According to an account issued tonight by Tass, much of Gorbachev's report focused on the economy and efforts to accelerate growth.

While noting a rise in industrial growth of 5.7 percent this year compared to the same period last year, Gorbachev said the Soviet Union has only begun to restructure its economy, a process that he said was "making slow progress."

Gorbachev sharply criticized "those who continue to work in the old way," Tass said. He stressed that the party would not slacken its struggle against "irresponsibility, red tape and other negative phenomena."

The draft plan to be adopted by the Supreme Soviet is largely in accord with targets set in March by the Communist Party congress. The congress also selected new Central Committee members, reflecting wide-scale personnel changes put into effect by Gorbachev.

In his report today, Gorbachev again focused on the era of Leonid Brezhnev -- the 1970s and early 1980s -- as a time when the Soviet Union "to some extent lost dynamism."

A key problem was "serious errors in capital investment policy," he said, particularly in manufacture of machine tools and instruments and computer technology.

No personnel changes were announced today, and a Tass report mentioned that Vladimir Shcherbitsky, party leader of the Ukraine and a Politburo member, was one of those taking part in discussion on the report.

Western diplomats saw this as a sign that Shcherbitsky, seen as a political outsider in the Gorbachev era, has survived the immediate political aftermath of the Chernobyl accident.