With little fanfare, the government of Indonesia this morning released 2,000 prisoners arrested, but never charged, during anti-government actvities in the mid-1960s.

The ceremony in Semarang, in central Java, was attended only by minor military officials and surviving family members of some of the prisoners. Officials have played down the release since the prisoners have been a continual source of embarrasment to the government of President Suharto.

A total of 27,307 people have been relased from custody during the past three years, according to government statistics, and officials say another 3,638 are to be freed during the next two months, virtually closing a grim chapter in the history of Indonesia.

The drama began in the early 1960s when the Indonesia Communist Party signed up about 3 million new members. The party subsequently was involved in an attempt to overthrow the government of the late president Sukarno on Sept. 30, 1965.

The precise events surrounding the abortive coup attempt have been the subject of much debate among foreign and Indonesian scholars. But no one disputes that reprisals engineered by Suharto, then an Army general, were aimed at eradicating Indonesia of all traces of communism.

Killings that followed the uprisings claimed at least 100,000 and possibly as many as 500,000 victims. The Army arrested another half million suspected member of the outlawed party.

"Those people were detained because of political unrest, not because of nothing," an influential official of the ruling Golkar Party said in commenting on today's release ceremony. "They were no just suddenly rounded up indiscriminately. This had been building up over a long period during the early 60s."

But Indonesia entered a traumatic period in the late 1960s as the mass arrests and long detentions split up the traditionally close-knit families of Javanese culture.

The government divided them into three categories: those considered hard-lined members of the Communist Party and instigators of the coup; those believed involved in the party and the coup, but against which the government has no concrete evidence; and prisoners only marginally involved with the communists.

Known ringleaders of the 1965 coup, such as Gen. Supardjo and Col. Untung were executed shortly after the takeover attempt. And government officials said all prisoners marginally involved were freed by 1972.

It is the second group that has remained in limbo, many for as long as 13 years.The government has brought no charges against most and thus has not brought them a trial.

Statistics are often subject to change in Jakarta and government figures on the number of prisoners are no exception. Authorities officially put the number at nearly 30,000 as late as 1977 when "operation supernatural" as the release program is known, began while the London-based Amnesty Internation and the British campaign for the release of Indonesian political prisoners contend the number was actually much higher.

The great discrepancies led a former attorney-general, Lt. Gen. Sugih Arto, to joke, "It is impossible to say exactly how many political prisoners there are. It is a floating rate, like the Japanese Yen vis-a-vis the dollar."

Such light-hearted attitudes onthe part of some Indonesians toward the plight of people held without charge only heightened the outcry against the Suharto government.

Much of the criticism is leveled at a penal colony to which about 11,000 people were exiled, including all those released this morning. Located on Buru Island in the Maluku Chain, prisoners lead tedious lives at hard labor in paddy fields. Some were popular poets, scholars and respected intellectuals prior to their arrest.

Officials said about 60 prisoners attempted to escape from the island over the years. None succeeded. The lucky ones returned to their prison camps. The others are believed to have died in the island's steaming tropical jungles. Journalists characterized Buru as a modern-day "Devil's Island."

Along with the publicity about conditions on Buru Island came President Carter's condemnation of human rights violations. As a recipient of more than $200 million in U.S. aid annually, Indonesia was one of the major targets of Carter's human rights campaign.

Suharto unveiled "operation supernatural power" about the time criticism peaked. But as the prison camps began emptying, leading officails repeatedly denied the government was acting under foreign pressure.

The releases will make it easier for the United States to continue pouring aid into Indonesia, but "operation supernatural power" is proving a mixed blessing for the prisoners.

Scenes of rejoicing have been markedly absent at release ceremonies. During festivities held last month, East Java military commander Maj. Gen. Witarmin congratulated the prisoners for earning the right to rejoin society. Then he unemotionally added that former prisoners found trying to resurrect the Communist Party "would be shot on the spot."

Nearly 100 prisoners offered freedom, whose families and friends have long forgotten them, have even chosen to remain on Buru Island.