SEOUL, South Korea (AP) _ Two U.S. Olympic swimmers left the country today after a government prosecutor decided not to file charges against them for taking a stone carving from a hotel bar.

Gold medal winners Troy Dalbey and Dough Gjertsen and a third American departed a few hours after prosecutor Yoo Sung-soo announced that he was dropping the case.

''The case is closed and no charges will be filed,'' Yoo said.

Yoo said earlier he had notified the U.S. Embassy in Seoul that the three Americans could leave South Korea on Saturday. Their sudden departure today was believed aimed at evading media attention and was not expected to cause legal problems.

The prosecutor said he decided not to charge the three Americans because they wrote statements repenting and had apologized to the South Korean people.

The case attracted nationwide attention with hundreds of Koreans calling newspapers and police to demand the swimmers be punished and prevented from leaving the country.

The case was a subject of harsh criticism in a protest letter delivered by radical students to the U.S. Embassy today. The letter from Seoul National University denoucned the alleged theft by the swimmers as an example of American arrogance.

Dalbey, Gjertsen and Ernest Mangum, who identified himself as a friend of the two swimmers, were questioned by police for allegedly stealing an $830 marble lion's head carving from a Seoul hotel last Saturday.

The two swimmers said in a statement Tuesday that they were being exuberant and the incident was a prank to celebrate their gold medal victories in two Olympic events the previous day.

The two apologized publicly and said they hoped the incident would not damage relations between the United States and South Korea.

Police said Dalbey and Mangum admitted removing the democration, but investigation showed Gjertsen was not involved.

The incident received wide publicity because it took place at a time of growing anti-U.S. sentiment among South Koreans during the Olympics. A series of incidents involving U.S. athletes and news media touched of a wave of anti- Americanism.

Many South Koreans are displeased by the disorderly conduct of U.S. athletes during the opening ceremony of the Olympic Games. NBC television also came under fire for its allegedly ''biased'' coverage of a boxing bout, during which South Korean sports officials attacked a referee.