Mikhail S. Gorbachev on Friday night closed a national Communist Party conference on his program of ``perestroika,'' saying resolutions endorsed by the delegates lead the way to a ``democratic image of socialism.'' The four-day conference, the first held by the party since 1941, was unprecedented in the openness of criticism of past and present leaders. Gorbachev pointed out one key to the four-day conference _ the attempt to overcome the party's Stalinist legacy _ when he called for construction of a monument to the victims Josef Stalin. ``I think we must agree to this, and such a monument must be constructed in Moscow,'' he said in his closing address. ``This would be an honest step, and it will be supported by the entire Soviet people.'' Gorbachev spoke after the conference of 5,000 party members adopted resolutions in what the Tass news agency called an ``unusually stormy and long'' debate. The meeting, which was called by Gorbachev to pass judgment on his 3-year-old policy of restructuring Soviet society, formally closed after his address. The Soviet leader also engaged in a long critique of the work of former Moscow party boss Boris N. Yeltsin, who appealed earlier in the day to the conference to absolve him of blame for criticizing the pace of Gorbachev's reforms last fall. That criticism cost Yeltsin his job and his spot as a candidate member of the ruling Politburo. Summing up the work of the conference, Gorbachev said, ``Through democratization, economic reform and changes in the political system we willmake perestroika irreversible. We will reach a fundamentally new state of our society, a new human and democratic image of socialism.'' He called for the policy-making Central Committee and other organs to urgently settle questions related to political reforms so they can begin to be implemented at a fall session of the Supreme Soviet. Referring to his proposals to restructure the government's legislative branch and give the president new powers, Gorbachev said ``the conference will continue living in the society, in the discussions in the society, but now we know how we must transform the political system.'' Tass said the conference adopted a package of six resolutions, saying the debate on bureaucracy, inter-ethnic relations and Gorbachev's policy of ``glasnost,'' or more openness, were particularly thorny. It did not say what the resolutions said. The Tass report said there were several votes on amendments, and that the conference rejected proposals by space scientist Roald Sagdeyev on elections to government councils. An amendment calling for the Communist Party newspaper Pravda to be taken out of the hands of the policy-making Central Committee received only 56 votes, it said. Gorbachev praised the open atmosphere of the conference. ``One of the heroes of our conference was glasnost because our conference was a result of the atmosphere of sincerity that is being reflected in our society. We also discussed its limits,'' he said. He called on the Soviet media to ``publicize the real achievements of the real heroes of perestroika,'' and proclaimed that no one has a monopoly on the truth. In an apparent reference to the time of Stalin, he said ``the printed word was a servant of arbitrary totalitarianism.'' In contrast, he said the conference had showed how the interparty debate must be carried out. Before the conference debate ended, however, the long-simmering feud between Yeltsin and Kremlin No. 2 leader Yegor K. Ligachev broke into the open. Yeltsin was judged as being politically mistaken by the party, but he said Friday his only mistake was poor timing. Gorbachev said Yeltsin was chosen to run the Moscow party organization because of his experience and energy, but ultimately proved he could not handle the job. Ligachev, at whom much of Yeltsin's criticism was leveled, took the floor Friday evening to oppose his return, saying Yeltsin committed many errors and still hadn't learned his lesson. The 57-year-old Yeltsin, a leading reformer and former protege of Gorbachev, was fired from his Moscow job as head of the Moscow Communist Party after he attacked the slow pace of reform during a speech in October to the Central Committee. The speech has not been published. Yeltsin was reassigned as first deputy of the state construction committee, a ministerial-level post. He was dropped from the Politburo in February but retained sufficient status in the party to be chosen a delegate. ``I think my only mistake was that I spoke too early, before the 70th anniversary of the October Revolution,'' Yeltsin said. It was a time when the party was trying to display unity and celebrate its successes. ``Taking to heart what happened, I ask the conference to change the decision of the plenum of the Central Committee,'' Yeltsin told the delegates. ``If you find it possible to do this, you will rehabilitate me in the eyes of Communists.'' Yeltsin took the floor to answer questions from many delegates about the circumstances of his ouster and about his demand that Ligachev resign. He had told Western reporters during the U.S.-Soviet summit meeting in Moscow that Ligachev was the party official most responsible for holding back Gorbachev's reforms. Ligachev said Yeltsin had ``not drawn the necessary conclusions from his mistakes and the principled criticism of his party comrades.'' Other delegates also criticized Yeltsin, charging that he had been tactless on a visit abroad and gave interviews to foreign new agencies just to boost his own prestige. Some rose to Yeltsin's defense in an open debate. Earlier Friday, the nation's top environmental official demanded punishment for planners responsible for pollution disasters, and a reformist publisher defended the new openness of the press. At other times during the conference, delegates have openly disagreed on the concrete results of Gorbachev's drive for perestroika, which was launched after he took power in March 1985.