South Korean marines plan to hold a drill on the island of Yeonpyeong in the disputed waters of the Yellow Sea [AFP]
North Korea's military has raised its alert for artillery units based along its west coast ahead of a planned live fire drill by the South, Yonhap news agency has reported, quoting a government source.
The move raised tensions that were already running high as the UN Security Council met for an emergency session on Sunday in an attempt to prevent the escalating crisis on the Korean peninsula from spiralling out of control.
Vitaly Churkin, the Russian UN Ambassador, who called a news conference on Saturday about the spat between North and South Korea, said he hoped the 15 council members could agree on a unanimous statement that would send a "restraining signal" to both Seoul and Pyongyang.
Bad weather had so far delayed the South's planned firing drill at the disputed border, the prospect of which has enraged North Korea.
The stand-off between the two Koreas has triggered fears among the international community that their spat could quickly spiral out of control.
Both sides have said they will use military means to defend what they say is their territory off the west coast.
"We understand that there's been an upgrade in alert at artillery units," Yonhap quoted a South Korean government source as saying. South Korea's defence ministry offered no immediate comment.
China and Russia have called on both Koreas to avoid actions that could inflame tensions.
Washington has backed Seoul's push to go ahead with the planned live fire drill on Yeonpyeong island, where four South Koreans were killed in an artillery attack last month.
The drill, within eyesight of the North Korean mainland, is scheduled to take place sometime before Tuesday.
North Korea has called the artillery fire drill by the South a suicidal war move that would trigger a full-out conflict on peninsula and said it would strike back in self-defence.
The South has said if was attacked in the same manner as last month, it would hit back hard with air power and bombs.
Analysts are sceptical the North would carry through with its threats to hit the South even harder than last month's bombardment if shells landed in its territory again.
Exercise to go ahead
The North will likely respond by holding a live-fire drill on its side of the tensely guarded sea border if the South goes ahead with its exercise, analysts said.
Weather conditions worsened on the normally sleepy island, which has been largely abandoned by residents after the November 23 attack.
The South Korean government, widely criticised at home for its perceived weak response to the shelling of the island, remained determined to carry out the exercise despite calls to reconsider.
"There is no plan to cancel the exercise. The factor we're looking at is the weather condition," a defence ministry official said.
South Korean marines plan to test artillery firing from the island targeting its territorial waters to its southwest, the same type of exercise that North Korea last month called an attack and prompted its shelling of the island.
North Korea continued with a blistering verbal assault on the South and the US at the weekend, accusing Seoul of conspiring with Washington to bring hostility against it.
The North's foreign ministry spokesman said in a statement: "We will be sure to settle scores with the US for the extreme situation on the Korean peninsula."