A team of U.S. technicians will on Monday start disabling North Korea's nuclear complex which makes weapons-grade plutonium, a senior U.S. envoy said on Saturday, under a multinational disarmament deal.

U.S. officials estimate the North has about 50 kg (110 lb) of plutonium. Proliferation experts say that is enough for six to eight bombs.

They will begin the process of disabling the DPRK (North Korea) plutonium production facilities in Yongbyon, Christopher Hill, the top U.S. envoy to six-way talks to end Pyongyang's nuclear arms program, told a news conference in Tokyo.

They will be going to Yongbyon tomorrow, and by Monday they'll begin their work.

North Korea has agreed to fully disclose all its atomic activities by the end of the year, and Hill confirmed that during his visit in Tokyo.

So by the end of the year ... we hope to have arrived at an important milestone where there is a complete disablement of the Yongbyon facilities, he said.

Where there is a full list of additional facilities which also need to be disabled, and the uranium enrichment matter is also resolved to mutual satisfaction.

The moves follow a breakthrough February deal under which North Korea, which tested a nuclear device last year in defiance of international warnings, is to shut down its Yongbyon nuclear plant and admit U.N. nuclear monitors.

In exchange, the impoverished North will receive 1 million tonnes of heavy fuel oil or equivalent aid. The United States will also move towards taking North Korea off a U.S. terrorism blacklist.


Experts say that though the disablement steps are reversible, it would prevent North Korea from going back to producing any more plutonium for about a year.

The view was also echoed by Hill.

We came up with a list of measures ... we believe, make sure even if today or even if on a certain day the North Koreans wanted to restart the plutonium -- which by the way will be a very bad day for all of us -- that it would take them well over a year to do that.

The steps, however, are short of outright destruction.

The North is required to provide a complete accounting of its fissile material and nuclear arms program by the end of this year under the deal it reached with China, Japan, Russia, South Korea and the United States.

Hills told NHK public broadcaster in an interview that North Korea had to make clear it had not supplied nuclear know-how to Syria.

Now they've (North Korea) made a pledge that there will be no transfer, he said.

But we're not just interested in pledges here, we're interested in verifying that, in fact, there is no such proliferation going on.

Western analysts say a tall boxy building, part of a site bombed by Israel in September, may have contained a nuclear reactor under construction similar to North Korean design.

Syria denies such speculation.

Separately, Japan's Kyodo news agency said on Saturday that Hill's North Korean counterpart indicated that Pyongyang would include a suspected uranium enrichment program in the declaration of its nuclear programs that must be submitted at the year-end.

Kyodo said Kim Kye-gwan, who met Hill on Wednesday, was speaking to reporters in Beijing.

(Additional reporting by Toshi Maeda)