Richard Starr, a Peace Corp volunteer kidnaped almost three years ago by this country's most powerful rural guerrilla group, the Armed Revolutionary Forces of Colombia, was released yesterday and is on his way to the United States, the American Embassy said today.

The embassy spokesman said negotiations were handled by "private negotiators" but refused to say who they were or whether the Columbian government had agreed to release any imprisoned guerrillas, as had been demanded, in exchange for the 34-year-old American botanist.

Reports of Starr's safe release reached here from Nava, a village about 200 miles southwest of Bogota, where an Army station confirmed that he had been brought to the town yesterday. An embassy official said Starr was in good physical condition despite the captivity that began Feb. 14, 1977, in the town of La Macarena, where Starr was assigned to a botanical study.

The Colombian radio station RCN declared that Starr's release came through negotiations conducted by American journalist Jack Mitchell, who came on behalf of columnist Jack Anderson.

[In Washington, Anderson said his office began negotiations with the guerrilla group in September after he wrote a column appealing for release of Starr and offering to serve as an intermediary. Mitchell met with representatives of the guerrillas in Mexico five months ago, according to Anderson, and they demanded $250,000. ]Associates of Anderson said he raised the money through private contacts and Mitchell took it to Colombia last weekened. The associates said the State Department maintained its policy of refusing to negotiate with kidnapers but did telephone Anderson's office at 1 a.m. Tuesday to say Starr was freed.

[Secretary of State Cyrus Vance issued a statement saying Starr's release "is cause for rejoicing for all Americans" and thanking "all those who over these long years have worked to achieve his release."]

The freeing said Starr ended a drama that provoked considerable interest here, where political kidnappings and abductions for ransom have reached alarming proportions in recent years and have led, in turn, to a determined crackdown on leftist guerrilla groups by Colombia's elected government.

Under a security statute approved by President Julio Cesar Turby Ayala in September 1978, police and military forces are given extraordinary powers to detain and question suspected guerrillas.

Human rights groups have charged that the subsequent antiguerrilla campaign has resulted in torture and lack of due process. A three-member team from Amnesty International spent two weeks in Colombia last month investigating these charges.

According to Colombian and diplomatic observers, the campaign has cut back such urban guerrilla groups as the M19, which until last year was capable of mounting raids against military installations and carried out both political kidnapings and others designed to obtain funds.

However, outside the major cities in this nation of 25 million people, the Turbay government has been less successful. Leftist revolutionary groups such as the Armed Revolutionary Forces, which is said to be an appendage of this country's legal, Moscow-line Communist Party, control whole sections of remote rural areas -- where the guerrillas kidnap and kill if necessary to enforce their control.

Starr was kidnaped from the village of La Macarena, about 150 miles south of Bogota in a mountainous jungle area, after guerrillas seized the town where he was working as a volunteer. Although Rosalynn Carter expressed concern about his fate when she visited Colombia in 1977, the U.S. government refused to enter into negotiations with the guerrillas for Starr's release.

The guerilla band would occasionally issue bulletins saying that Starr was still alive, offering to exchange him for prisoners held by the government. wThese offers were always turned down. Meanwhile, Starr's mother, Charlotte Starr Jansen of Spokane, Wash., made several trips here and issued public appeals for her son's release. She described him as "a gentle person who has empathy for people." Her stateside efforts reached to columnist Anderson.

Because of Starr's kidnaping and a general climate of violence or uncertainty because of emerald and drug smuggling as because of the leftist guerrrillas -- the Peace Corps limited its program in many sections of the country. It is still active in Bogota and other cities.

Starr's release follows that of William F. Niehous, an American businessman who was rescued by Venezuelan authorities from his guerrilla captors after being held from February 1976 until last July.

Venezuela, to the east of Colombia, has largely solved its guerrilla problem by a policy of offering amnesty to those who surrender. Colombia's government has pursued a policy of arresting guerrillas and sentencing them to long jail terms.

More than 300 alleged guerrillas are now on trial here, most of them members of the urban M19 group that seized more than 4,500 weapons in a spectacular raid on an Army arsenal early last year.

The Colombian Rebel Armed Forces is thought to number about 800 activists. It claims at least 11 currently active fronts in rural areas.