SINGAPORE — South Korea has asked the United Nations Security Council to take action against North Korea over the sinking of a South Korean warship, the South Korean president said Friday.

“It is important for us to encourage North Korea to admit its wrongdoing,” President Lee Myung-bak of South Korea said at an international security conference here. “It must pledge to never again engage in such reprehensible action. This is the interest of peace, this is in the interest of North Korea.”

South Korea did not specify what action it was seeking from the Security Council for the sinking of its warship, the Cheonan, which it says was torpedoed by the North on March 26. But any Security Council action would have to be approved by China, which holds a veto in the Council and is an ally and major trading partner of North Korea.

Beijing has yet to weigh in on the report by a South Korean-led international investigative team that concluded that North Korea was responsible for the ship’s sinking, which killed 46 South Korean sailors and raised tensions between the Koreas to their highest level in years.

In a letter submitted to the Council on Friday, South Korea asked that it “respond in a manner appropriate to the gravity of North Korea’s military provocation,” the South Korean ambassador to the United Nations, Park In-kook, said, adding that the action should be strong enough to deter any similar attack in the future.

Meanwhile, the United States defense secretary, Robert M. Gates, said that joint military exercises with South Korea might be delayed until after the Security Council met on the issue.

The possible delay of the joint exercises was seen in South Korea as an effort to avoid provoking China. The Security Council is in the midst of negotiating the final language on new sanctions against Iran, expected next Thursday, and on the reaction to the Israeli raid on the flotilla bound for Gaza, so any action on North Korea will most likely wait at least a week, Council diplomats said.

South Korea has been lobbying its allies to bring some form of Security Council censure against the North since May 20, when it formally accused the North of sinking the ship.

In Singapore on Friday, Mr. Lee portrayed the sinking as part of a historical pattern of North Korean aggression rather than as an isolated event, saying that North Korea had “repeatedly attacked us time and time again.”

He cited the 1983 North Korean attack on South Korean cabinet members in Burma, now Myanmar, that killed 17 South Korean officials, and the 1987 bombing of a Korean Airlines jet that killed 115 people.

Speaking to the same conference on Saturday morning, Mr. Gates echoed the point. “This sinking is far more than a single, isolated incident, with tragic results for the sailors and their families,” he said. “It is, rather, part of a larger pattern of provocative and reckless behavior.”

He said that the United States would support action in the Security Council and that it was “assessing additional options to hold North Korea accountable.”

But Chung Min Lee, a foreign policy adviser to President Lee, said that the president “has basically told the North Koreans, ‘If you do this type of provocative act one more time, we will respond with some kind of military response.’ ”

Neil MacFarquhar contributed reporting from the United Nations, and Thom Shanker from Washington.