WARSAW, FEB. 12 -- The Soviet Union said today it will not meet Polish demands for a withdrawal of its troops from Poland by the end of this year, deepening an already acrimonious dispute over the issue between the two formerly close allies.

In a meeting with Polish President Lech Walesa, a senior Soviet diplomat said withdrawal of the 55,000 troops would not be completed until mid-1994, in part because the Soviet Union had no place to house the returnees and their dependents.

It was the first time the Soviets have spelled out exactly how long they intend to take to pull their troops out of Poland. The statement came on the same day that the Kremlin announced it would meet a demand of Eastern European countries and dissolve the Soviet-dominated Warsaw Pact military alliance by April 1. {Story, page A16.}

Poland is the only country in the region that has not signed a troop withdrawal agreement with the Soviet Union, and the stalemate could derail the scheduled exit of a half-million Soviet troops from eastern Germany. Poland has said it will block Soviet troop transit across its territory until a date is set for troop withdrawal here.

Until early this year, the withdrawal of Soviet troops from Eastern Europe had moved quickly and relatively smoothly. Tens of thousands of Soviet soldiers already have left Czechoslovakia and Hungary, and a gradual, three-year withdrawal has been agreed upon for the huge Soviet troop presence in Germany.

But Poland appears to have been caught short by the current ascendancy of political hard-liners in Moscow and the weakening of the reform faction around President Mikhail Gorbachev. A top aide to Walesa said last week that the troop withdrawal has been complicated because it is connected to developments in Soviet domestic politics.

Soviet generals involved in pullout negotiations here have struck a progressively inflexible and bellicose tone in recent statements. They have ridiculed the Polish insistence that departing Soviet troops be moved in civilian clothes and without weapons.

Soviet generals also have complained that Poland is not sufficiently grateful for 45 years of Soviet military "protection" and accused the Poles of treating Soviet soldiers as "invaders and international criminals" and of trying to send them home "in disgrace."

Polish Deputy Defense Minister Janusz Onyszkiewicz referred recently to the change in Soviet tone as "an enormous stiffening" and said he hoped Poland would not have to resort to cutting supplies of gas, water and food to the troops to force them to leave.

A Polish Foreign Ministry spokesman said today that the Soviet timetable -- withdrawal beginning in May and continuing to mid-1994 -- "is too long for us."

Teams of Polish and Soviet negotiators convened in Warsaw this week for the fourth in a series of emotionally charged meetings intended to hammer out conditions under which the Soviet troops will go home.

Foreign Ministry spokesman Wladislaw Klaczynski said the date for withdrawal "must be resolved at the highest government level." He said the government had not ruled out a meeting between Walesa and the Soviet defense minister.

But while Poland's elected government is eager for a speedy troop pullout, its ministers say they realize that Poland is in no position to press too hard for it.

Polish Defense Minister Piotr Kolodziejczyk declared last week that his country had adopted a status of "armed neutrality in middle Europe." While the Warsaw Pact was all but defunct, he said, Poland has no plans to join the NATO alliance any time soon.

As a neutral country with a powerful eastern neighbor, Poland has no interest in irritating the Soviet Union further, Kolodziejczyk said. "The political strategy of our state appreciates the fact that the Soviet Union, despite its problems, will remain a superpower," he said.

The troop issue has become the major sticking point in Warsaw's relationship with Moscow. Poland depends on the Soviet Union for most of its oil and natural gas, for the bulk of its foreign trade and to provide parts and equipment for its military.

The hardening tone of Soviet negotiators also has raised Polish fears that hard-liners in the Soviet Union will use the troop issue to drive a wedge between Poland and Germany, but Czechoslovakia moved to support the Polish position last week by announcing that it too would block transit of Soviet troops from Germany until the Polish question is settled.

Poland's insistence on closely managing the pullout arises partly from the experience of Czechoslovakia. About three-quarters of the 73,000 Soviet troops once stationed in Czechoslovakia have left, reportedly amid wholesale vending of their equipment, uniforms and even of plumbing fixtures from their barracks. There also have been numerous reports of live ammunition being dumped or sold by departing Soviet soldiers.

Last month, the Czechoslovak news agency reported that children in northern Bohemia had discovered detonators, signal rockets and ammunition in a garbage dump outside a Soviet barracks and that a man had found a full machine-gun belt in his garden.

In a related Polish-Soviet dispute, the Polish government recently blocked for nearly three weeks a Soviet military truck convoy carrying medical and other supplies to Russian Orthodox Church congregants until the Soviets met Polish requests that the convoy be licensed and insured and that its drivers travel unarmed and in civilian clothing.