The unofficial human rights committee here known as the Helsinki Group announced its disbandment today, a move that symbolized an end to organized internal political dissent in Moscow.

The group, which was organized six years ago to monitor Soviet compliance with the human rights provisions of the 1975 Helsinki agreement, has been dormant for more than a year. Only three members had escaped exile or prison.

The decision to terminate activities was taken after one of the remaining members, lawyer Sofia Kalistratova, was advised by the prosecutor's office Monday that she would face charges of anti-Soviet activities in connection with her distribution of material about Soviet human rights violations.

Yelena Bonner, wife of Nobel Peace Prize winner physicist Andrei Sakharov, said another factor leading to the decision to disband the group was that some of its imprisoned members due for release were having their sentences doubled.

In a statement, the group said: "In these circumstances, the group cannot fulfill the obligations it assumed and under pressure from the authorities is forced to end its work."

Kalistratova, 75, has been defense attorney for several political dissidents, including former major general Pyotr Grigorenko and writer Vladimir Bukovsky. Both men currently live in the West.

Sakharov, a founding member of the group and its most prominent voice, was banished to the city of Gorki two years ago. Other co-founders, including physicist Yuri Orlov and Jewish activist Anatoly Scharansky, are imprisoned.

With Kalistratova and Bonner, the other member not in jail or exile is mathematician Naum Naiman, 67, who has been trying to emigrate to Israel for the past eight years.

The group has issued 194 documents about alleged abuse of human rights in the Soviet Union and has managed to send many of them to the governments which signed the Helsinki final act. Virtually all European countries as well as the United States and Canada attended the 35-nation Helsinki meeting, which began as a Soviet initiative.

According to Bonner, some documents were confiscated by Soviet police during several searches of Kalistratova's aparment and these form the basis for the charges.

At one point, the Helsinki Group had branches in various Soviet cities. But by mid-1980 nearly all organized dissident activities had ceased. Security forces have intensified efforts to stamp out organized political dissent, especially after the turmoil in Poland where Soviet commentators contend a small group of dissidents has played a key role in organizing an opposition.