South Korea ups defence of sea border with North

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SEOUL, June 2 (Reuters) - South Korea on Tuesday bolstered its defence of a disputed naval border with an increasingly belligerent North Korea, deploying a guided-missile naval vessel to Yellow Sea waters off the west coast, the South's navy said.

North Korea last week threatened to attack the South and said it would not guarantee the safety of its vessels in waters near a border that has been the site of two deadly clashes between the rival states in the past 10 years.

South Korea typically does not announce specific deployments related to defence against the North, with which it is still technically at war because their 1950-53 conflict ended with a cease fire and not a peace treaty.

But in a signal it will stand firm over the disputed sea border, South Korea sent the 440-tonne vessel named Yun Yeong Ha, equipped with anti-ship missiles and heavy guns, to reinforce its fleet of high-speed naval vessels there, the navy said.

North Korea has stepped up its military training, stockpiled ammunition and imposed a no-sail order off its west coast waters to prepare for a possible fight with the South, the South's biggest newspaper Chosun Ilbo reported a South Korean military source as saying.

North Korea has stoked tension in the past days with a nuclear test on May 25 and firing a barrage of short-range missiles off its east coast. (Reporting by Jon Herskovitz and Kim Junghyun, editing by Jonathan Thatcher and Sanjeev Miglani)