West Germany's Social Democrats sharpened their dispute with the government over missile deployment today by charging that the Soviet Union is preparing to install short-range nuclear rockets in Eastern Europe in response to the planned deployment of U.S.-built medium-range nuclear missiles in Western Europe later this year.

Egon Bahr, the Social Democrats' disarmament expert, told parliament that the Soviets are surveying sites in Poland, East Germany and Czechoslovakia for SS22 missiles that could strike West Germany within two or three minutes of launching.

But Defense Minister Manfred Woerner called Bahr's claim "a new legend" and said the Soviets already have stationed modern SS21 missiles, with an 80-mile range, in East Germany and maintain older nuclear missile systems in other Eastern European states.

The bitter exchange illustrated the mounting political tensions here as the Social Democrats drift toward an alliance with the peace movement and Bonn's center-right government braces for possible violent protests this fall against its plan to install the first nine Pershing II missiles by Dec. 15 if the Geneva arms talks fail to achieve a compromise.

Since leaving power in October, the Social Democrats have grown increasingly disenchanted with the U.S. negotiating tactics in Geneva and have called for conciliatory overtures, including a moratorium on deployment, to reach an arms control agreement that would make it unnecessary to station the powerful Pershing IIs in West Germany.

The ruling Christian Democrats, in turn, have castigated the Social Democrats for breaking the West's security consensus and encouraging the Soviets to exploit such splits through a propaganda campaign fostering public opposition to the deployment of new nuclear weapons.

In today's security debate in parliament, Bahr accused the Reagan administration of distorting the so-called "twin-track" strategy, approved by the Western Alliance in 1979, which calls for the deployment of nuclear missiles to counter the Soviet Union's comparable arsenal of more than 350 SS20s unless the Geneva talks produce a compromise by the end of 1983.

Bahr argued that President Reagan, Secretary of State George P. Shultz and Secretary of Defense Caspar W. Weinberger have twisted the rationale of the twin-track strategy by saying recently that no serious negotiations should be expected with the Soviets until the West proceeds to deploy the new cruise and Pershing II missiles.

"If it had been stated in 1979 that the Americans expected no serious negotiations until after the missiles were deployed, there would have been no twin-track decision," Bahr declared.

The Social Democrats will decide whether to oppose deployment at a special party congress in Bad Godesberg on Nov. 2. Barring a sudden breakthrough at the Geneva talks, party leaders said recently that more than 90 percent of the delegates may vote against plans to install the missiles.

Chancellor Helmut Kohl insists, however, that his government will abide by commitments to deploy the Pershings on schedule in the absence of an arms control agreement.

The Social Democrats and leaders of the peace movement have criticized the government's green light for preparation of the Pershing II sites. Recent reports indicated that building of the infrastructure is well under way and that parts of the missiles are already in the country.

The Social Democrats' board agreed Monday to propose a bill in parliament that would halt the introduction of missiles or any parts into West Germany before the next round of negotiations end in Geneva on Nov. 15.

Leaders of West Germany's 26 disparate peace groups have unveiled plans for a series of demonstrations and blockades of missile sites that will culminate in three massive assemblies of more than a million people in Bonn, Hamburg and Neu-Ulm near Stuttgart--reputedly one of the Pershing II sites --on Oct 22.

Andreas Zumach, a spokesman for Action Reconciliation Peace Service, the largest Christian pacifist group, accused the government of seeking to turn public consternation over nuclear weapons into hysteria about anarchic missile protesters.

Interior Minister Friedrich Zimmermann recently warned about a "hot autumn" and predicted violent clashes between soldiers and demonstrators.