Seoul: South Korea will hold a major military exercise near the disputed Yellow Sea border with North Korea later this month on the eve of a global forum in Seoul, officials said on Wednesday.

The drill involving warships, jet fighters and marine units will be staged on March 25 as part of events to mark the second anniversary of the sinking of a corvette, the defence ministry said.

Seoul accused its neighbour of torpedoing the ship on March 26, 2010, with the loss of 46 lives. The North denied responsibility for the sinking but shelled a South Korean border island eight months later, killing four people.

The exercise will show "our firm readiness to punish" any provocations by the North, a senior ministry official told reporters.

He said soldiers would hold drills or rallies separately at their barracks on March 26, when dozens of national leaders including US President Barack Obama gather for the Nuclear Security Summit in the capital.

The summit will focus on ways to safeguard atomic material worldwide and prevent acts of nuclear terrorism. The North has blasted it as an "unsavoury burlesque" intended to justify an atomic attack by South Korea and its US ally.

Pyongyang's new leaders have agreed a nuclear deal with the United States but have taken a consistently hostile tone with the South's conservative government and its President, Lee Myung-Bak.

The North has several times threatened to launch a "sacred" war against the South over what it sees as insults to new leader Kim Jong-Un and his late father Kim Il-Sung.

The South's Yonhap news agency said today that about 130 North Korean officials visited the tense land frontier last week as Pyongyang intensified its threats.

US and South Korean military officials had no comment on the report.