North Korea threatened on Thursday to cut all ties with South Korea saying the new conservative government is pro-US and engaged in reckless confrontation with its neighbor.

North Korea has been unhappy with South Korea's new President Lee Myung-bak, who took office in February with a pledge to get tough on the rival state. By contrast, Lee's two liberal predecessors had aggressively sought reconciliation by providing massive aid to the impoverished nation.

The North's warning, issued in a commentary carried in the North's main Rodong Sinmun newspaper, said if the South "keeps to the road of reckless confrontation with the (North), defaming its dignity despite its repeated warnings, this will compel it to make a crucial decision including the total freeze of the North-South relations."

That means Pyongyang could terminate civilian exchanges with the South, including a tourism program and a joint factory park.

North Korea already has suspended all government-level dialogue and exchanges, though the sides met as part of broader international negotiations on Pyongyang's nuclear programs. It has also rejected a food aid proposal and dialogue offers from the South, saying those offers lacked sincerity.

The North made a similar threat during military talks with the South earlier this month, saying it would expel South Koreans from the tourism and industrial projects if propaganda leaflets critical of Pyongyang keep arriving over the border.

No immediate steps

South Korea played down the threat.

"It does not mean the North will take steps immediately," said Unification Ministry spokesman Kim Ho-nyeon. "We will monitor the situation regarding this, and there is no change in the government's intention to improve South-North relations through dialogue."

North Korea has branded the South's president a "traitor," "pro-American sycophant" and "despicable human scum."

"The Lee group is becoming more frantic in its racket of confrontation with the (North) in league with outside forces," Thursday's commentary said, calling Lee "so hell-bent on sycophancy towards the US and confrontation with fellow countrymen."

The warning came days after North Korea resumed a stalled nuclear disarmament process after the United States removed it from a terrorism blacklist, and amid lingering questions about the health of the North's leader Kim Jong II.

"The North is putting strong pressure on our government as its relations with the United States are improving and its negotiating power is gaining strength," said Hong Hyun-ik, an expert at the security think tank Sejong Institute. "It's a sort of brinksmanship strategy."

Yang Moo-jin, a professor at Seoul's University of North Korean Studies, said the North is trying to show that its warning made earlier this month "was not empty language."

South Korea suspended a tour program to the North's Diamond Mountain after a South Korean woman was shot dead by a North Korean soldier in July during a tour. Other civilian exchanges have proceeded, including another tour program to the North's ancient border city of Kaesong and a joint factory park nearby.

The three programs have been considered prominent symbols of inter-Korean reconciliation. But they have also been criticized for providing hard currency to North Korea that could be used for its nuclear program.

The two sides fought the 1950-53 Korean War that ended in a truce, not a peace treaty, leaving the peninsula technically still at war. Their ties had warmed significantly since the first-ever 2000 summit of their leaders before freezing again this year.