Moscow's dissident human-rights monitors, the ''Helsinki group,'' have formally disbanded, battered and bitter from a six-year contest with the authorities.
The announcement came Sept. 8 from Yelena Bonner, wife of exiled physicist Andrei Sakharov. Mrs. Bonner is one of the three active members who have so far escaped arrest, prosecution, or confinement.
The move came almost 11 months to the day after a senior official of the KGB security apparatus, writing in the Communist Party's main ideological journal, in effect claimed victory over organized political dissidence. The article charged that Western intelligence services had hoped to sow the seeds of organized struggle against the Soviet system, but that ''they failed to set up a cohesive organization on a basis of anti-Sovietism.''
Since its founding in May 1976, the ''Helsinki group'' here had churned out 194 typewritten statements detailing alleged Soviet violations of human-rights provisions in the Helsinki Accords.
Mrs. Bonner issued No. 195. Less than a single page in length, it charged that Soviet authorities had inflicted ''cruel persecution'' on the Moscow group since its inception and had, on Sept. 6, threatened possible prosecution of 75 -year-old Sofia Kalistratova, a retired lawyer and another of the handful of group members still active. The third member is 70-year-old Naum Meiman, a retired physicist who has been denied permission to emigrate from the Soviet Union.
The statement, signed by the three, concluded with the words:
''In this increasingly difficult situation the group cannot fulfill the duties it assumed and, under pressure from the authorities, it is ending its work.''
The official crackdown on the Moscow group began in earnest with the 1977 arrest of its founder, physicist Yuri Orlov. About a year later, a court sentenced him to seven years in a labor camp and five years in internal exile. There followed the imprisonment or exile of nearly all of the roughly 20 dissidents active in the Moscow group at one time or another. The authorities also moved against members of similar groups in the Ukraine, Lithuania, Georgia, and Armenia.
If Yuri Orlov's confinement was a blow to the Moscow group, the 1980 banishment of physicist Andrei Sakharov to the city of Gorky was surely another. By early this year the associated ''Helsinki group'' in the United States all but predicted the eventual demise of the Moscow organization.
Mrs. Kalistratova, a statement from the US group alleged, had already been told by the KGB of plans to prosecute her for ''circulation of fabrications . . . which defame the Soviet state and social system.'' This was deemed ''a great blow to the Moscow group,'' which ''could signify the end of its activities.''
On Sept. 6, the group's final statement suggests, Mrs. Kalistratova received a second notification of the case against her. She was told she would receive definitive word within the next few weeks on whether the state prosecutor's office would press ahead with a trial.