North Korea accused South Korea Tuesday of being gripped by war hysteria and said the situation on the peninsula has reached "an unpredictable stage."

Rodong Sinmun, official daily of the ruling communist party, blasted the South's President Lee Myung-Bak as a "reckless and arrogant traitor."

"The situation on the Korean peninsula is being driven to an unpredictable stage," the newspaper said in a commentary entitled "(The South) is seeking to ignite a nuclear war."

Such comments have appeared for months as ties soured, but they follow an unusually strongly worded message from the North's military at the weekend.

The South's military ordered a border alert Saturday after a spokesman for the North's army General Staff said it would adopt an "all-out confrontational posture" against Seoul.

The General Staff warned it would not allow intrusions by South Korean vessels into what it termed North Korean waters, raising fears of clashes along the disputed border in the Yellow Sea.

It was the first statement from the General Staff for 10 years.

Some analysts say the statements are aimed at the incoming US administration rather than Seoul. They say the North wants to persuade Washington not to sideline it despite a daunting array of other global problems.

Others say the warning should be taken seriously.

"The belligerent Lee Myung-Bak and his cliques... are madly dashing down the path toward a war aggression against the North and their war hysteria has gone beyond the limits," Rodong Sinmum said.

Another commentary in the paper, entitled "Digging their own graves," said South Korean "warmongers" had called for full preparations for a possible clash in the disputed waters.

Inter-Korean relations have been frosty since Lee linked major economic aid to progress in the North's nuclear disarmament, and international nuclear disarmament negotiations are stalled.

The North staged its first nuclear test in 2006 but four months later reached a disarmament pact with the US and four regional powers.

Progress on the 2007 pact has halted because of disagreements about how the North's disclosure of its nuclear activities should be independently verified.

Despite the tensions a South Korean delegation visited the North last week to discus the possible purchase of unused fuel rods from its plutonium-producing plants.

The plants at Yongbyon are being disabled under the current phase of the 2007 pact.

The team led by deputy chief nuclear envoy Hwang Joon-Kook arrived home Tuesday but Hwang gave no information on whether any deal is likely.