They did attend but with their own banners and orders of the day. The security agency of the Netherlands, in a confidential paper prepared for a meeting of NATO security officials late in 1981, linked the International Department of the Soviet Communist Party and the Communist Party of the Netherlands in a coordinated effort to influence the nuclear attitudes of Dutch church groups. 'Instructions From Moscow'

Directly dealing with the K.G.B., it said, ''it is known that K.G.B. officers in the Netherlands have received instructions from Moscow to promote protests against the neutron bomb, but it is difficult to ascertain how they have put these instructions into practice.''

The Dutch security agency, however, documented a K.G.B. forgery, sent to activists, newspapers and politicians that purported to be a U.S. military paper revealing that the United States Pershing 2 and cruise missiles were part of a strategy aimed at making a limited nuclear war in Europe possible.

According to an American intelligence specialist, the decisive point for the Soviet effort to block deployment will come in the fall, when West European countries expect violent confrontations with demonstrators.

''The question then,'' he said, ''will be how hard the K.G.B. pushes. We know it has catalogues of shouters, marchers, street fighters, bomb throwers and killers it could turn loose. They can pick one from Column A, another from Column B. They could arrange a provocation, have a demonstrator shot with a stolen U.S. Army .45, or any number of things. Those are K.G.B. jobs and serious business. The only question for them is evaluating the margin of risk of a potential backfire and the possibility of satisfactory yield.'' 'Agents of Influence' in the West

Stanislav Levchenko, a K.G.B officer who defected to the United States in 1979, goes along with the view that the Soviet Union does exert influence in the West through Western Communist parties. But he also offers the view that it would be totally out of character for the K.G.B. to fail to concentrate on running ''agents of influence'' - often people willing to defend Soviet positions without formal recruitment - who can guide public positions of groups opposed to nuclear weapons.

''I think that 99.9 percent of the people active in the peace organizations are honest,'' Mr. Levchenko said in an interview, adding in regard to asapirations of the Soviet officials: ''But they want a leader or two. They want somebody who stays late to write out the platform when they go home to bed. Those people stay busy. Sometimes it's just a slogan. But the degree of Soviet success so far has been great. The buildup of criticism on nuclear weapons by these groups has gone basically in only one direction - against NATO.''