April 1 (Bloomberg) -- North Korea denounced South Korean President Lee Myung Bak as a ``traitor'' and a ``sycophant toward the U.S.'' in its first critical comments using his name since he took office in February.

Lee ``revealed his true colors as a sycophant toward the U.S. and anti-North confrontation advocator as soon as he came to power,'' North Korea's official Korea Central News Agency said today, citing the Workers' Party newspaper Rodong Sinmun.

North Korea stepped up criticism of South Korea when the U.S. and South Korean governments began putting pressure on the communist country to disclose all its nuclear programs after it failed to meet a pledge to make a declaration by Dec. 31.

Christopher Hill, the chief U.S. nuclear negotiator, arrived in Seoul today to discuss North Korea with South Korean officials. There was little progress on the declaration when Hill met with North Korean Vice Foreign Minister Kim Kye Gwan in Geneva last month. He has no immediate plans to meet North Korean officials, he said today in Seoul.

Lee, who took office Feb. 25, pledged to take a tougher line on North Korea than his predecessors and said a lack of progress in the nuclear dismantlement process would harm ties between the two countries.

`Sycophancy, Confrontation'

``The Lee Myung Bak regime of the Grand National Party that emerged in South Korea recently is becoming undisguised in its sycophancy toward the U.S. and confrontation with'' North Korea, KCNA cited the newspaper as saying.

The denuclearization of the Korean peninsula is ``not an issue between the North and the South but an issue between the DPRK and the U.S. and an international issue. That was why the six-party talks were arranged,'' the newspaper said. The Democratic People's Republic of Korea is the official name for North Korea.

The U.S. and South Korea, along with China, Japan and Russia, are involved in talks to persuade North Korea to dismantle its nuclear weapons program.

North Korea and South Korea are technically still at war since their 1950-53 conflict ended in a truce rather than a peace agreement.

Hill, who serves as assistant secretary of state, said North Korea's comments on the South Korean president were ``obviously completely inappropriate,'' and aimed at a ``domestic audience, whoever they are.'' He once again urged North Korea to fulfill its pledge to hand in an ``accurate and complete declaration'' of its nuclear programs.

`Lost Time'

``They need to include a complete description of their nuclear programs.'' Hill said after a dinner meeting with his South Korean counterpart Ambassador Chun Yung Woo in downtown Seoul today. ``We really have lost a lot of time in this process and we need to go forward. We're really at a point where we need this declaration.''

``It's time to settle now,'' Hill told reporters when he arrived at Incheon International Airport outside Seoul earlier today. ``Obviously we are getting to the point where we need to make some progress very quickly. I don't have a specific deadline.''

Hill said before he left Washington yesterday that the other members of the six-nation forum are running out of patience with North Korea.

U.S. and South Korean officials have called on North Korea, which carried out a nuclear weapons test in October 2006, to issue an ``accurate and complete'' declaration, including details of a suspected uranium-enrichment program.

`Long Enough'

`` We've waited long enough,'' South Korea's chief nuclear negotiator Chun said, after meeting with Hill. `` There is no reason for North Korea to delay in handing in the declaration.''

The two negotiators discussed ``ways to go forward in this process,'' Chun said, but declined to elaborate.

In July, North Korea shut down the Yongbyon nuclear reactor, which produced weapons-grade plutonium, under the first phase of the six-party accord reached in February 2007.

It began disabling the reactor under the supervision of U.S. inspectors in November. It must finish that process and declare the details of its nuclear programs to complete the second phase. The third and final phase includes the dismantling of its nuclear program so that it can't be rebuilt.

Uranium Enrichment

North Korea on March 28 reiterated its denial that it was enriching uranium and warned that continued U.S. accusations that it operates such a program may harm the six-party talks. It accused the U.S. of delaying the six-nation process.

Two days earlier, the government in Pyongyang ordered South Korean officials to leave North Korea's Gaeseong industrial complex. Some 52 South Korean companies use the complex as part of their country's policy of engagement with its neighbor.

``In our (U.S. and North Korean) discussions regarding the six-nation talks, we've not had the kind of tone shown by the KCNA,'' Hill told reporters in Seoul. ``We've made it clear that these statements are very unhelpful.''

North Korea test-fired ``several'' short-range missiles into waters off its western coast on March 28 as part of a regular military exercise, South Korea said last week. It was North Korea's first missile test in nine months.

On March 30, North Korea threatened to cut off talks with South Korea over a report in the JoongAng Ilbo newspaper that a South Korean military official discussed a possible pre-emptive strike on the communist nation. The Defense Ministry later denied there was any mention of such a strike.

North Korea still wants to ``develop North-South relations and achieve independent reunification, peace and prosperity,'' KCNA said in its report. The country will keep to its June 2000 agreement between North Korean leader Kim Jong Il and then-South Korean President Kim Dae Jung to work toward reunification.

To contact the reporter on this story: Heejin Koo in Seoul at hjkoo@bloomberg.net.

Last Updated: April 1, 2008 08:50 EDT