The guns fell silent on July 27, 1953 under the armistice accord but hostilities never officially ended on the Korean peninsula.

The threat of war has reappeared in recent months during a crisis over North Korea's nuclear weapons ambitions.

Panmunjom straddles the military demarcation line that runs through the centre of the heavily fortified demilitarized zone (DMZ) that divides communist North Korea from the capitalist South.

Standing on the southern side of the line, US veteran Lawrence Hardman, 70, from West Virginia, said the sacrifice made during the 1950-53 war was worth it.

"If the North Koreans started to move across that line right now, I'd grab myself a rifle and do it all over again," said Hardman, who joined the 187th Airborne and was shipped to Korea in 1952.

Some 2,500 people, including 900 veterans from the 16 countries of the US-led United Nations fighting force, attended the ceremony which North Korea described as a "very dangerous act" at a time when the risk of a far more destructive war was rising.

The nuclear crisis erupted nine months ago when Washington said North Korea had admitted to running a clandestine nuclear weapons program in violation of a 1994 pact.

North Korea has demanded a non-aggression accord and direct talks with Washington while the United States has been seeking multilateral talks to resolve the nuclear threat.

South Korean President Roh Moo-Hyun, in a speech marking the anniversary, said ending the nuclear stalemate was the most urgent task facing the country.

"North Korea should come to the forum of dialogue as early as possible," he said.

New Zealand Prime Minister Helen Clark, who held summit talks with Roh on Friday, delivered the keynote speech at the Panmunjom ceremony.

North Korea "must abandon its nuclear weapons and other weapons of mass destruction," she said, expressing an "earnest hope" that the crisis be resolved peacefully."

During the week leading up to the armistice anniversary, a diplomatic push by China, North Korea's closest ally, appeared to be bearing fruit and officials in Seoul spoke of negotiations resuming as early as August.

A round of three-party talks among China, North Korea and the United States was held in Beijing in April. The United States is insisting that South Korea and Japan be included in further talks.

In North Korea, armistice day is celebrated as a victory in "the Fatherland Liberation War".

Pyongyang's official media spoke Sunday of celebrations across the country but also seized the anniversary to warn of a new war.

"The army and the people of the DPRK (North Korea) do not want a war. But they are not afraid of and will not avoid it," said Rodong Sinmun, North Korea's ruling party mouthpiece.

The armistice was never replaced by a peace treaty and 37,000 US and some 700,000 South Korean troops face off against North Korea's 1.1 million strong army over a border that remains one of the world's most dangerous flashpoints.

An estimated four million people, most of them civilians, died during the three-year Korean War.

Veterans who remembered the Korean peninsula as a moonscape of mud and scorched earth said they were gratified to see that South Korea, 50 years on, had prospered.

"I was hungry, cold and scared to death most of the time," said Elmer Frick, 72, who served with the US 45th Infantry Division. "But looking around me at South Korea today, I wouldn't trade the experience for anything."

Armistice anniversary ceremonies conclude later Sunday with a wreath-laying ceremony and a 21-gun salute at US army headquarters in downtown Seoul.

WAR.WIRE