Three Chinese Navy ships that entered South Korean waters searching for a torpedo boat were driven off today after "warning demonstrations of force" by South Korean warplanes and ships, officials in Seoul said.

The incident began yesterday with an apparent mutiny by Chinese torpedo boat sailors who were seeking to defect, sources in Seoul said. Shooting broke out on the boat, and six of its 19 crew members were killed and two wounded. The fate of the other 11 crew members was not reported. The boat developed engine trouble and began drifting in the Yellow Sea.

According to South Korean Defense Ministry spokesman Lee Hong Shik, at 11 a.m. yesterday a South Korean fishing boat responded to a distress call from the torpedo boat, and towed it to the South Korean island of Hawangdung, 120 miles southwest of Seoul. News agencies reporting from Seoul said the boat was found near the island of Sohuksan, off the southwestern tip of the Korean Peninsula.

The arrival in South Korea of the Chinese torpedo boat raises new complications for the two countries' cautious efforts to open relations with one another.

It was the first confrontation in many years between the two countries' armed forces, which battled each other during the Korean War and have not established formal diplomatic relations since. However, the Chinese vessels turned back, the Chinese diplomatic response was low key and tension was defused.

In Washington, State Department spokesman Brian Carlson said South Korea asked that the United States act as an intermediary between Seoul and Peking.

"We were asked to convey some messages between the Koreans and the Chinese in the early stages of the incident, and we did," Carlson said. "We believe the two governments will be in touch directly from now on." He declined to reveal details of the diplomatic communications.

The initial Chinese reaction today was to say only that contact had been lost with a Navy torpedo boat. Then tonight, the Chinese Foreign Ministry issued a statement describing the entry of Chinese Navy ships into South Korean waters as inadvertent and asking the South Koreans to return the boat as well as its crew members "as soon as possible."

A western diplomat described the tone of the Chinese statement as reasonable and said it indicated that China was "not going to do anything foolish" toward South Korea over the boat incident.

"While searching for the boat, Chinese naval vessels inadvertently entered South Korean waters," the Chinese statement said. "As soon as they found this, they left the above waters on their own. No incident took place.

"The torpedo boat in question is still somewhere along the South Korean coast," the statement continued. "We request the South Korean side to assist in returning in an appropriate way the boat and all its crew members to our side as soon as possible."

At least one of the Chinese sailors reportedly requested political asylum. Two crew members were taken to a hospital and treated for bullet wounds. They were reported to be in good condition.

The vessel was identified in South Korean government photographs as No. 3213 in the Huchuan class, The Associated Press reported from Seoul. According to Jane's Fighting Ships, Huchuan-class boats have a top speed of 55 knots and a 500-mile range.

Today, the South Korean government told its diplomatic mission in Hong Kong to protest the ships' intrusion, according to reports in Seoul.

In deciding its next move, South Korea will have to balance its firm anticommunist ideology against its desire for closer ties with China.

China and South Korea have been expanding informal ties slowly in recent years. They now have trade of several hundred million dollars per year in commodities that include oil, coal and manufactured goods. They exchange sports teams and semiofficial delegations.

South Korea apparently hopes the contacts will reduce tension on the Korean Peninsula, loosen Chinese ties with Communist North Korea and develop a vast new market for its industry. Seoul also appears to want the international prestige to be gained from de facto recognition by China.

China also seems to view the ties as a means of reducing tension. Its modernization programs also stand to benefit from links with South Korean industry.

A spokesman in Seoul for the 40,000 U.S. troops stationed in South Korea said that U.S. forces were not involved in the incident in any way.

The incident marks South Korea's fourth experience with defecting Chinese in the past 2 1/2 years.

In November 1982 and again in August 1983, Chinese MiG jet fighters were flown to South Korea, and both pilots were allowed to leave for Taiwan.

In May 1983, six Chinese citizens hijacked a Chinese airliner during a domestic flight and forced it to South Korea. They were given lengthy prison terms by a South Korean court but were released last year by special order and allowed to go to Taiwan.

Paradoxically, the hijacking served to draw the two countries closer. A few days after it took place, China sent its first-ever official government delegation to Seoul to negotiate the return of the plane and its passengers.

Washington Post correspondent Daniel Southerland in Peking and special correspondent Young H. Lee in Seoul contributed to this report.