A major split is developing in West Germany's peace movement between those seeking to enlist broad public sympathy through nonviolent tactics and others who believe that more aggressive action is necessary to block the basing of nuclear missiles here later this year.

This growing schism worries West German authorities, who suspect that the pacifist wing may become discredited should the Geneva arms talks fail and the Pershing II missiles be deployed in December.

If that happens, it is widely thought that the antimissile crusade could turn to violent assaults on military targets in West Germany.

West Germany's peace movement, which claims up to 3 million members in the population of 61 million, has announced plans to climax the autumn campaign with an "action week" starting Oct. 15. It is to feature protests each day by supporters in churches, schools, women's groups, factories and government institutions.

Thousands of demonstrators intend to form a human chain 60 miles long stretching from headquarters of the U.S. forces European Command in Stuttgart to one of three Pershing II missile sites in Neu Ulm. On Oct. 22, more than 300,000 people are expected to march through Bonn and blockade several ministries. Similar peace rallies are scheduled to take place the same day in other West European capitals.

The week of demonstrations may be the last chance for nonviolent advocates to show that the peace movement can lure the masses into the streets and impress the government with the argument that opinion polls are correct in showing that nearly three-quarters of West German citizens are opposed to the stationing the missiles here.

Until now, the antimissile campaign has emphasized peaceful forms of protest, mostly sit-ins and rallies. This strategy held that if police tried to bully crowds, a sense of moral outrage would sweep the country and mobilize the kind of mass support that can dictate a change in policy, if not in government.

But three weeks ago, in what was billed as the first test in a "hot autumn" of protests, a three-day blockade of the Mutlangen U.S. Army base by about 3,000 protesters fizzled when the authorities simply halted traffic and let the demonstrators bask in their passivity.

In a series of post-mortems since the ineffectual blockade, several protest leaders have clamored for a "strategy of escalation," including strikes, occupation of military bases and possible acts of sabotage.

More forceful tactics by the peace movement, argues Lukas Beckmann, general manager of the Greens party, would still exclude violence against people but not "the damaging of material objects."

Another Greens party leader, Rainer Trampert, warned recently that the peace movement was in danger of being "blunted" by devotion to law and order and said it had to display a new "quality of resistance" through more aggressive acts even at the risk of losing some supporters.

"Mutlangen showed that the police are only nice to us if we are particularly harmless," he said.

As the likelihood grows that Pershing II missiles will be deployed, the current factional dispute over tactics could evolve into a deeper division between nonviolent activists and those who feel that any means are acceptable in halting nuclear weapons.

While some of the peace movement's marginal supporters may lapse into apathy or find solace in new causes, West German authorities are bracing for bursts of guerrilla-type violence in the months ahead.

Internal security officials have been investigating reports of planned bombing attacks against U.S. munitions transports in West Germany. A Defense Ministry spokesman denied last week that munitions deliveries and shipments were being suspended for the next two months as a precaution against possible attacks.

The right-wing daily Die Welt charged last week that a group known as the "Red Panthers," derived from previous underground terror cells of the Red Army Faction that carried out kidnapings in the last decade, is actively preparing "direct attacks" on military installations as early as this fall.

The newspaper cited a security report contending that Red Army Faction supporters were responsible for arson attacks against arms companies this summer and also participated in violent disturbances at Krefeld in July when Vice President Bush's motorcade was attacked by rock-throwing protesters.

As a disparate movement, the Greens party includes some influential personalities from previous decades of leftist student revolt and its violent aftermath. Otto Schilly, a Greens member of parliament and lawyer, actively defends radical causes and has pleaded cases for arrested members of the Baader-Meinhof gang.

The Greens party's leaders have deplored protests related to assaults on other people and dissociated themselves from the attack on Bush's limousine. Petra Kelly, another leading figure in the antimissile drive, said the rock-throwers "were punks, that's all. They had nothing to do with the peace movement."

But some Greens leaders are now criticizing their own allies for accepting a docile relationship with the authorities.

Ulrich Tost, a member of the Greens' executive committee, criticized left-wing Social Democrats and trade union officials in the peace movement for "taking part in a double strategy by the police to split the peace movement into good and bad sides and eliminate the aggressiveness of civil disobedience."