Seoul, South Korea ? North Korea launched a blistering propaganda counterattack Sunday, saying the United States had pushed relations to the brink of war and that South Korea was guilty of “noisy, false propaganda” over the sea battle in which four southern sailors were killed.

The belligerent North also refused as the “height of impudence” the South’s demand for an apology and again said the sea border along which the fight took place was an illegal boundary imposed by the United States at the end of the 1950-53 Korean War and should be redrawn.

The United States maintains 37,000 troops in the South to prevent a resumption of fighting, which ended in an armistice but has never been made official through a peace treaty.

The South Korean military said North Korea suffered about 30 casualties in the fight Saturday, though independent confirmation was not possible. Without elaborating, North Korea said it suffered losses.

The battle broke out Saturday morning after two North Korean patrol vessels accompanying fishing boats crossed the sea border, South Korean officials said. Seoul claimed one of the northern patrol boats opened fire after ignoring warnings to retreat. North Korea, however, accused the South of starting the fight by entering what it claimed was communist-controlled water in the Yellow Sea.

The fighting was worst clash between the Koreas in three years. Besides the four South Korean sailors who died, 19 among the 27-member crew were injured. One sailor was missing after the patrol boat sank.

The sea border was calm Sunday, and South Korean President Kim Dae-jung was in Japan to watch the World Cup soccer final and meet Japanese leaders. He was expected to return today to Seoul.

North Korea has been lashing out at the United States since President Bush last January lumped the country together with Iran and Iraq as “an axis of evil.”

“This is a declaration of a showdown of strength on the Korean peninsula and an extremely dangerous attempt to drive North Korea-U.S. relations to the brink of war,” said Rodong Sinmun, the newspaper of the North’s ruling Workers’ Party.