North Korea is the world's foremost vendor of missile technology and has "one of the most robust offensive bioweapons programs on earth," the top U.S. arms negotiator said Thursday, echoing President Bush's warnings about the communist state.

U.S. Undersecretary of State John Bolton called North Korea "an evil regime that is armed to the teeth, including with weapons of mass destruction and ballistic missiles."

"President Bush's use of the term 'axis of evil' to describe Iran, Iraq and North Korea was more than a rhetorical flourish -- it was factually correct," Bolton said in a speech to a a group of South Korean government officials and scholars.

"There is a hard connection between these regimes -- an axis along which flow dangerous weapons and dangerous technology," he said.

The chief U.S. arms-control negotiator was in Seoul for a three-day visit that included talks with South Korean officials on the communist North's arms proliferation. He discussed the same topic with Japanese officials in Tokyo earlier this week.

His comments come at a sensitive time, as the two Koreas try to revive stalled reconciliation after months of tension. South Korea wants Washington to open dialogue with Pyongyang about the arms issue.

Bolton stressed that such overtures will depend on whether the North will stop developing and exporting missile parts and technology to "notable rogue state clients such as Syria, Libya and Iran."

He said North Korea is "the world's foremost peddler of ballistic missile-related equipment, components, materials, and technical expertise."

Bolton also warned that a 1994 deal to provide North Korea with two power-generating nuclear reactors will be "in serious doubt" unless North Korea quickly allows U.N. inspections of its suspected nuclear weapons program.

Despite its denial, the Central Intelligence Agency suspects that the North may have stockpiled enough plutonium to make one or two atomic bombs before freezing its nuclear program in 1994.

Bolton also said that there is "little doubt" that North Korea has an active chemical weapons program and has "one of the most robust offensive bioweapons programs on earth."

As Bolton spoke, economic officials of the two Koreas were meeting in Seoul to discuss a host of pending issues, including a cross-border railway. The talks were part of an agreement reached during Cabinet-level negotiations in Seoul earlier this month.

The revived inter-Korean dialogue has coincided with North Korea's moves to reach out to the rest of the world.

In July, North Korea agreed to accept a visit by a special U.S. envoy. It held normalization talks with Japan earlier this week.

Some analysts in Seoul were critical of Bolton's speech.

"Bolton's speech casts gloom over President Kim Dae-jung's policy of engaging the North," said, Kim Tae-woo, a research fellow at the government-funded Korea Institute for Defense Analyses. "It signals that a rough path is ahead in relations between Washington and Pyongyang."

The United States fought on South Korea's side in the 1950-53 Korean War. About 37,000 U.S. troops are stationed in South Korea as a deterrent against the North.