North Korea has warned of "unpredictable consequences" if the US and South Korea go ahead with today's planned naval exercises in the Yellow Sea.

The massive naval war games have angered Pyongyang and its ally Beijing, and South Korea's president Lee Myungbak has warned there could be "further provocation" from the North.

Nuclear-powered carrier the USS George Washington and its battle group is heading for waters west of the Korean peninsula for four days of exercises.

Washington has stressed that the Yellow Sea manoeuvre is "defensive in nature", was planned before North Korea's attack, and is not aimed against China.

The United States also says that its display of naval firepower will act as a "deterrent" to the volatile regime of Kim Jong-Il, which has kept the region on edge for years with its nuclear and long-range missile tests.

But North Korea's official KCNA news agency issued an ominous warning: "If the US brings its carrier to the West Sea of Korea (Yellow Sea) at last, no one can predict the ensuing consequences".

The divided Korean peninsula is locked in the worst crisis in decades, triggered by North Korea's bombardment of the small border island of Yeonpyeong, located near their flashpoint maritime border.

The North said it was responding to live fire by South Korea into its waters.

Two marines were killed in the attack, along with two civilians. Many others were wounded and a number of houses caught fire.

An opinion piece published in North Korea's state-run media said any civilian deaths from its artillery attack were "very regrettable".

But it added that the deaths were South Korea's fault for treating civilians as "human shields".

South vows revenge

The slain marines, Sergeant Suh Jung-Woo, 22, and Private Moon Kwang-Wook, 20, were laid to rest during a nationally-televised funeral service in Seoul yesterday.

The marines' commander, Major-General Yoo Nak-Joon, told mourners at the ceremony that their deaths will have grave repercussions.

"We will certainly avenge your deaths. All marines, including marines on service and reserve marines, will avenge the two at any cost, keeping today's anger and hostility in mind," he said.

"We will put our feelings of rage and animosity in our bones and take our revenge on North Korea."

Around 1,000 South Korean veterans have marched through Seoul to protest against what they say is their government's weak response to North Korea's attack.

- ABC/AFP