SEOUL (Reuters) - Top U.S. arms negotiator John Bolton described North Korean leader Kim Jong-il on Thursday as a tyrannical dictator who lived like royalty while jailing thousands and keeping many hungry in a "hellish nightmare."

In a tough speech guaranteed to provoke a blistering North Korean response, the undersecretary of state also said Kim was mistaken if he thought threats to proliferate nuclear weapons would weaken international resolve to halt Pyongyang"s atomic ambitions through multilateral talks.

His comments come at a delicate time. Japan"s Kyodo news agency said the United States, China and North Korea were discussing a proposal to hold three-way talks in early September.

"The last year has seen Kim Jong-il accelerate these programs, particularly on the nuclear front," he said in a speech to the East Asia Institute, referring to proliferation.

"The days of (North Korean) blackmail are over," he said. "Kim Jong-il is dead wrong to think that developing nuclear weapons will improve his security."

Bolton, widely seen as a hawk on North Korea, painted a stark picture of life for North Koreans with Kim at the helm.

He mentioned Kim"s name some 40 times, and described him as one of the world"s "tyrannical rogue state leaders" who needed to introduce sweeping reforms or face economic ruin.

"While he lives like royalty in Pyongyang, he keeps hundreds of thousands of his people locked in prison camps with millions more mired in abject poverty, scrounging the ground for food," he said.

"For many in North Korea, life is a hellish nightmare."

North Korea is edging toward nuclear talks but has recently repeated its demand Washington its "hostile policy."

TWO OTHER TRACKS

Bolton, on a three-country tour that will take him next to Tokyo, said the United States and its allies were trying to persuade North Korea to start multilateral talks on ending its nuclear weapons program.

Secretary of State Colin Powell told Reuters in Washington on Wednesday that he saw the "distinct possibility" of more multilateral talks this year with North Korea, China and perhaps others aimed at resolving the crisis.

North Korea wants bilateral talks with Washington, a line Bolton described as a "one-note piano concerto." He said it would be highly irresponsible for Washington to hold one-to-one talks.

He other tracks should be pursued too, including the U.N. Security Council taking "appropriate and timely action."

"Unfortunately, the Council is not playing the part it should," he said. "To date, virtually nothing has happened."

Bolton, who visited China before Seoul, said 11 countries would continue efforts to try to thwart North Korean exports of weapons and other illicit goods.

The countries are members of the "Proliferation Security Initiative" and are considering intercepting assets.

"Kim Jong-il would be wise to consider diversifying his export base to something besides weapons of mass destruction and ballistic missiles," Bolton said.

On the talks, he said Pyongyang had yet to agree on the format. South Korean security adviser Ra Jong-yil said it would be difficult for the United States, China and North Korea to hold talks in early August. They held inconclusive talks in April.

A U.S. combat team equipped with state-of-the-art fighting vehicles was arriving in South Korea on Thursday for training. The North"s official KCNA news agency said it was "a scout party to ignite another war of aggression." (Additional reporting by Teruaki Ueno in Tokyo and Samuel Len in Seoul)