North Korea has singled out South Korea's president for harsh criticism, for the first time since he took office. Meanwhile, the chief American envoy to talks aimed ending North Korea's nuclear weapons is in Seoul, warning time is "running out" for the North to fulfill its diplomatic promises. VOA Seoul correspondent Kurt Achin reports.

South Korea's President Lee Myung-bak (file photo)

North Korean media has lashed out against South Korean conservatives on a number of previous occasions - but Tuesday's commentary is the first time Pyongyang has singled out President Lee Myung-bak, by name, referring to him as "a traitor."

A North Korean announcer says what he calls Lee Myung-bak's sycophantic approach to the United States and confrontational approach to North Korea are entirely to blame for the current stall in North-South relations. She says the Lee Myung-bak administration must accept full responsibility for the situation.

President Lee was inaugurated in February. He has introduced a much firmer policy line towards North Korea than his two predecessors. He says North-South relations - including economic cooperation and transfers of humanitarian aid - will be preconditioned on North Korea's cooperation in ending its nuclear weapons programs. A Tuesday editorial in North Korea's Rodong Shinmun warns of what it calls "irrevocable catastrophic consequences" for Mr. Lee's policies.

Pyongyang is now four months late in producing a declaration of its nuclear stockpiles and activities which it promised by the end of 2007. The delay has created a serious roadblock for negotiations between the North and China, Russia, Japan, the United States and South Korea.

Christopher Hill answers reporters' question upon his arrival at Incheon International airport in Incheon, South Korea, 01 Apr 2008

The chief American delegate to those talks, Assistant Secretary of State Christopher Hill, arrived in Seoul. He warns the delay cannot go on indefinitely.

"I hope we can figure out a way to get through this, but, obviously, we are kind of running out of time right now," said Hill.

The main sticking points of the stalled declaration are U.S. accusations the North pursued a secret uranium-based weapons program and suspicions Pyongyang may have helped Syria build a nuclear facility. The North has denied both allegations.

South Korean officials have kept quiet about Tuesday's media criticism from the North, which comes just days after North Korean media threatened to turn South Korea to a "sea of ashes." U.S. envoy Hill describes that editorial as "completely inappropriate and out of line."