(AP Photo/Yonhap) KOREA OUT)

SEOUL, South Korea - South Korea on Monday conducted live-fire military drills from five islands near its disputed sea boundary with North Korea, despite Pyongyang's threat to attack.

South Korea reported no immediate action by North Korea following the drills, which ended after about two hours. The drills took place in an area of the Yellow Sea that was the target of a North Korean artillery attack in 2010 that killed four South Koreans and raised fears of a wider conflict.

The heightened tension comes two months after the death of North Korean leader Kim Jong Il. His young son Kim Jong Un has taken the helm of the nation of 24 million.

South Korean military officials said they were ready to repel any attack. Residents on the front-line islands were asked to go to underground shelters before the drills started, according to South Korea's Defence Ministry and Joint Chiefs of Staff.

North Korea's military maintained increased vigilance during the South Korean drills, though it hasn't done anything suspicious, a South Korean Joint Chiefs of Staff officer said on condition of anonymity, citing department rules. He refused to provide further details because he said they involve confidential military intelligence on North Korea.

Before the drills began, North Korea said it would launch a "thousands-fold more severe" punishment than the 2010 shelling if South Korea conducted the drills.

North Korea is fully prepared for a "total war," and the drills will lead to a "complete collapse" of ties between the Koreas, the North's Committee for the Peaceful Reunification of Korea said in a statement carried Monday by the official Korean Central News Agency.

Seoul is closely monitoring North Korea's reaction. The Korean peninsula has been technically at war for about 60 years.

Officials from North Korea and the United States are to meet this week in Beijing for talks on the country's nuclear weapons program. The discussions will be the first such bilateral contact since Kim Jong Il's Dec. 17 death.

Ties between the Koreas plummeted following the 2010 shelling of front-line Yeonpyeong Island and a deadly warship sinking blamed on Pyongyang. North Korea has flatly denied its involvement in the sinking, which killed 46 South Korean sailors.

South Korean troops on the five islands fired artillery into waters southward, away from nearby North Korea, a Defence Ministry official said on condition of anonymity, citing department rules.

Residents on the islands, many of them elderly, filed into underground bomb shelters and huddled around portable heaters during the drills.

More than 1,000 people evacuated to shelters, but few came to the mainland, despite the North Korean threat, according to Onjin County, which governs the islands. Ferry services linking the islands and Incheon port on the mainland operated normally, county officials said. Officials say requests to evacuate are made each time South Korea conducts drills.

Soon after Seoul told Pyongyang of its live-fire training plans Sunday, North Korea's military called the drills a "premeditated military provocation" and warned it would retaliate for an attack on its territory.

A North Korean officer warned in an interview Sunday with The Associated Press in Pyongyang that North Koreans were always ready to "dedicate their blood to defend their inviolable territory."

The maritime line separating the countries was drawn by the U.S.-led U.N. Command without Pyongyang's consent at the close of the 1950-53 Korean War, which ended with a truce, not a peace treaty. North Korea routinely argues that the line should run farther south.

On Yeonpyeong Island, which is just seven miles (11 kilometres) from North Korean shores, about 490 people evacuated to shelters, while the rest of the 600 to 700 residents stayed at home or went to work as usual, an island official said in a phone interview, speaking on condition of anonymity because he wasn't authorized to talk to reporters.

South Korea also plans joint anti-submarine drills with the United States this week, but the training site is farther south from the disputed sea boundary, South Korean military officials said. About 28,500 U.S. troops are stationed in South Korea as what U.S. and South Korean officials call deterrence against North Korean aggression.

North Korea says joint U.S.-South Korea drills are a rehearsal for a northward invasion.