North Korea is set to blow up the cooling tower at its nuclear plant on Friday, a symbolic move to show its commitment to a disarmament deal a day after it handed over a long-delayed account of its nuclear programme.

Global powers still need to verify the claims Pyongyang made in its atomic inventory and experts say the dramatic event will leave unresolved questions about the North's declaration, such as accounting for its nuclear weaponry and proliferating technology.

The secretive North has invited in five foreign media outlets to witness the destruction of the tower, which is connected to its Soviet-era reactor. It is expected to come down in the afternoon local time.

Steam coming from the tower in spy satellite photographs has been the most visible sign of operations at the facility, designed to produce arms-grade plutonium.

"The problem is that they always feel that they can continue to game the system and appear to keep the window open - actions like blowing up cooling towers on TV for propaganda effect that I'm not sure have much practical effect," said Derek Mitchell, Asia expert at the Centre for Strategic and International Studies.

Christopher Hill, the chief U.S. envoy to six-way talks on ending North Korea's nuclear programmes, said in Japan on Friday that all the parties have received a copy of the declaration and will now move to verify its contents.

U.S. President George W. Bush on Thursday cautiously welcomed the declaration but warned North Korea, which tested a nuclear device in October 2006, that it faced "consequences" if it did not fully disclose its operations and continue to dismantle its nuclear programmes.

Responding to an unusual opening by the secretive communist state, Bush took a step towards removing North Korea from a U.S. list of state sponsors of terrorism and issued a proclamation lifting some sanctions under the Trading with the Enemy Act.

INCREASED INVESTMENT

Once it is removed from the lists, North Korea will be able to better tap into international finance.

Due to the small size of North Korea's rickety economy, any increases in investment and trade could have major effects, experts said, adding that increased revenue would likely make its way to Pyongyang's leaders and further solidify their rule.

"It will basically secure their legitimacy and their survivability," said Carl Baker, director of programmes at the Pacific Forum CSIS think tank in Hawaii.

U.S. officials acknowledged that the North Korean declaration, which came six months after a December deadline, fell short of answering all concerns about Pyongyang's atomic ambitions, especially on past nuclear proliferation activities.

Stephen Hadley, Bush's national security adviser, said the statement revealed the amount of plutonium North Korea had produced but did not detail its nuclear arsenal.

But he said U.S. experts could "do the math" and that issue would be discussed in a further phase of the so-called six-party talks.

Under a deal North Korea struck with China, Japan, Russia, South Korea and the United States, Pyongyang was required to start taking apart its Yongbyon nuclear plant and provide the nuclear list by the end of 2007.

U.S. and South Korean officials said North Korea has taken most of the steps to put the Yongbyon facility - that includes the reactor, a plant to make nuclear fuel and another to turn spent fuel into plutonium - out of business for at least a year.

"The key issue here is of course verification and what type of an inspection regime the North Koreans agree to," said Lee Chung-min, professor of international relations at Yonsei University in Seoul.

"Once we come down to the nitty-gritty of inspections, they will basically try to prolong the process as long as possible, without giving up nuclear weapons."