SEOUL - THE United States has agreed to sell bunker-buster bombs to South Korea that are capable of destroying underground facilities - including, potentially, nuclear sites - in North Korea, a military official said yesterday.

The United States recently approved the sale of the laser-guided GBU-28 bombs, used during the 1990-91 Gulf War to destroy underground command centres in Iraq.

The weapons will be delivered to South Korea between next year and 2014, South Korea's Yonhap news agency reported.

It said that, in the event of war, South Korean jet fighters would carry the bombs to attack underground targets, such as North Korea's nuclear facilities and artillery hidden in caves.

While North Korea's recent nuclear test and missile launches have captured world attention, military officials say the North's artillery - deployed in tunnels along the border - poses a serious threat to South Korea.

General Walter Sharp, the top US commander in the South, said in April that the North has the world's largest artillery force.

Meanwhile, North Korea's ailing leader, Mr Kim Jong Il, has named his third son, 26-year-old Swiss-educated basketball fan Jong Un, as the heir to his communist dynasty, reports said yesterday.

North Koreans were reported to be making pledges of loyalty to Jong Un and singing songs in praise of "General Kim".

The youngest Kim son has been described as a "chip off the old block" and is seen by experts as a potentially skilled and ruthless leader, like his father, who has kept his regime in place despite years of famine and economic decline.

Analysts have speculated that Pyongyang's recent sabre-rattling is intended primarily to shore up the older Kim's support within the powerful military, guaranteeing a continuation of the Kim dynasty.

In further warlike moves, it was reported yesterday that the North was readying three medium-range missiles for launch. US military officials have already confirmed that a long-range Taepodong-2 capable of striking the US was being prepped for launch.

North Korea was also strengthening its defences and conducting amphibious assault exercises along its western shore - possible preparations for skirmishes at sea, reports said.

South Korea has deployed a guided- missile, high-speed boat to the area to stamp out any provocations, the navy said.

-AFP