SEOUL, South Korea (AP) _ Two U.S. Olympic gold medalist swimmers and a third American were questioned by police today about the theft of a stone carving and both swimmers offered apologies to the Korean people.

Troy Dalbey and Doug Gjertsen were each questioned by police for two hours about the removal last Saturday of a marble lion mask worth $830 from a Seoul hotel. A third American, identified by police as Ernest Mangum, a friend of the swimmers, was also questioned in the case.

The case will be sent to the public prosecutor Wednesday for a decision on any further action, police said, adding that the Americans could be charged with aggravated theft with a possible prison sentence of one to 10 years.

At the police station, the swimmers read apologies saying they hoped the incident would not damage relations between the United States and South Korea.

''We want to apologize especially to the Korean people and hope our actions did not jeopardize the positive relations between the people of the U.S. and our gracious hosts in Seoul,'' Gjertsen said.

Dalbey said the incident was a prank committed in ''boyish exuberance to celebrate our Olympic victory.''

The swimmers, who won two gold medals each last week, were kicked off the U.S. team and told to remain in their quarters at the Athletes' Village while Korean authorities decide whether to prosecute them.

Police said investigations indicated that Dalbey and Mangum took the mask while intoxicated. Gjertsen did not appear to have been involved in the theft, police said.

U.S. diplomats escorted the three men to Yongsan Police Station where they were questioned.

Local officials, who declined to be named, said the apologies by the two swimmers could help resolve the case and it might be dropped in the next few days. The three cannot leave South Korean until the case is resolved.

In another development today, city officials said some 500 Olympic flags have been stolen or damaged near U.S. Army headquarters in Seoul.

Local authorities, who declined to be named, said the flags had disappeared or been damaged since late July in the area around the headquarters of the U.S. 8th Army in the Yongsang district.

Asked if they had any evidence that Americans took the flags, officials said they received reports from citizens that Americans were seen ripping down the flags.