South Korean soldiers patrol a seashore in Dangjin, about 120 km (75 miles) south of Seoul in this picture taken early December 21, 2010 and released on December 22, 2010. [Photo/Agencies]

SEOUL - South Korea will hold three-day drills in waters off the east coast of the Korean Peninsula starting Wednesday, two days after it conducted a live-fire exercise near a tense border, the defense ministry said.

The exercise, to be held about 100 kilometers south of the eastern sea border with the Democratic People's Republic of Korea( DPRK) from Wednesday through Friday, will involve navy vessels and Lynx anti-submarine helicopters, according to local reports.

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In a similar but separate move, South Korea also plans to stage on Thursday a major drill involving artillery guns and fighter jets at a firing range in Pocheon, 40 kilometers northeast of Seoul and 25 kilometers south of the heavily fortified land border between the two Koreas.

The exercise, aimed at testing fire power, will be a joint one between the army and the air force.

What officials say are part of routine exercises comes after South Korea staged firing exercise Monday from the western border island of Yeonpyeong, shelled last month by the DPRK.

The DPRK repeatedly vowed retaliation against the drill but did not immediately respond to what it called a "reckless" provocation.

Though saved from an immediate clash, South Korean forces remain vigilant against retaliation from the DPRK, deploying an Aegis destroyer and putting fighter jets on standby.

There are also concerns that a Christmas tree on the top of the Aegibong hill in the South Korean city of Gimpo, lit up a day ago, might be a potential target of the DPRK's strike for being a perceived anti-Pyongyang propaganda tool.

The annual ritual of lighting up the symbolic tree was suspended in 2003 as the two Koreas, amid a conciliatory mood, agreed to stop propaganda war.