The DPRK has put its military artillery units on high alert. The move comes ahead of a planned live-fire drill by South Korea. South Korean marines are likely to stage the drills off Yeonpyeong island near the peninsula's west coast some time before nightfall on Tuesday.

South Korea's drills were originally scheduled to take place on Sunday on Yeonpyeong Island, where four South Koreans were killed in an artillery attack last month.

A South Korean Defense Ministry official said the drills were delayed due to bad weather, and could take place on either Monday or Tuesday.

The ministry says the military's position to hold the drills remains unchanged.

The DPRK labeled the artillery fire drill by the South a move that would trigger an all-out conflict on peninsula.

Pyongyang warned the drills would trigger a more severe counter response than last month's artillery exchange. It also warned the US of the serious consequences in supporting South Korea's exercises.

News reader of DPRK KRT Television, said, "The US is wholly to blame for November's artillery exchange, as it instigated South Korean puppet forces to perpetrate the provocation. The entire international community, including neighboring countries, demand an unconditional halt to the dangerous shelling from the island. But only the US is openly encouraging South Korea to persist."

South Korea has said if was attacked in the same manner as last month, it would hit back hard with air strikes and bombs.

US troubleshooter New Mexico governor Bill Richardson is on a private mission to Pyongyang. He said he had made some progress in his discussions with officials there.

Richardson said he did not get a firm answer on whether the DPRK would physically strike the South again, but warned the situation remains very tense.