SEOUL, South Korea - North Korea threatened Sunday to retaliate against South Korea for taking it to the UN Security Council over the deadly sinking of a warship, calling the action an "intolerable provocation."

South Korea officially asked the UN Security Council on Friday to punish North Korea, accusing its nuclear-armed communist neighbour of blowing apart one of its warships with a torpedo, killing 46 sailors. It was the first time Seoul has taken Pyongyang to the Security Council for an inter-Korean provocation, despite a history of being attacked by the North.

On Sunday, North Korea -- which denies involvement in the sinking -- issued a statement saying the South's action will intensify military tension and could trigger a war on the divided peninsula.

"That is yet another intolerable provocation to us," the North's Committee for the Peaceful Reunification said.

The statement -- carried by the official Korean Central News Agency -- was Pyongyang's first response to Seoul's request for UN action over the March 26 sinking.

The North Korean committee said its military will launch a "stern punishment" against South Korea if it doesn't stop anti-North Korea steps. It didn't elaborate on what action it might take.

The Security Council has several choices: a resolution with or without new sanctions against North Korea, a weaker presidential statement calling for specific actions, or a press statement.

The Security Council earlier imposed sanctions against North Korea after its two nuclear tests in 2006 and 2009. These include UN embargoes on nuclear and ballistic missile-related items and technology, on arms exports and imports except light weapons, and on luxury goods.

UN diplomats familiar with consultations on possible action against North Korea said that China, the North's closest ally, is opposed to new sanctions and indicated that the more likely result will be a presidential statement. The diplomats spoke on condition of anonymity because the contacts have been private.

Just hours before the UN request was made Friday, conservative South Korean President Lee Myung-bak delivered a bare-knuckled speech at a defence conference in Singapore that accused North Korea of undermining global peace.

Lee said the ship sinking was a "reprehensible action" and that the North Koreans should not believe they can continue to "taunt" the South and "do whatever they want." If they continue, they will have "to suffer the consequences," he added.

On Sunday, Lee, however, toned down his criticism of North Korea in a Memorial Day speech that stressed the need for peace.

"We have an unachieved dream," he said in a speech at the national cemetery in Seoul. "It is to become a unified country living in freedom, peace and prosperity with North Korean compatriots who are still suffering from poverty and suppression."

Lee has taken a hard-line approach to North Korea, and his critics argue that the policy has antagonized the reclusive North and set the stage for the ship's sinking. In the past week, Lee's party suffered a serious defeat in local elections that were widely viewed as a referendum on the president in the middle of his five-year term.