The normally reclusive state had invited foreign media into the country to witness the tower's demolition, capitalising on its public relations potential, our correspondent said.

Al Jazeera's Melissa Chan, reporting from Beijing where Pyongyang handed over a much-delayed declaration of its nuclear programme declaration on Thursday, said the North Koreans appeared keen to have the image of the tower's destruction seen worldwide.

Broadcasters from each of the other five nations involved in the disarmament process were given a rare invitation to visit the country.

The blast was originally to have taken place at 02:00 GMT on Friday, but had been delayed by a few hours for unspecified reasons.

Nuclear declaration

Shortly after Beijing confirmed receiving the North's nuclear declaration on Thursday, George Bush, the US president, said Washington would start the process of taking Pyongyang off its list of state sponsors of terrorism.

"North Korea has begun describing its plutonium-related activities ... It has promised access to the reactor core and waste facilities at Yongbyon, as well as personnel related to its nuclear programme," Bush told reporters at the White House.

"The United States is responding to North Korea's actions with two actions of its own. I'm issuing a proclamation that lifts the provisions of the Trading With The Enemy Act... secondly, I am notifying congress of my intent to rescind North Korea's designation as a state sponsor of terrorism in 45 days."

He added that during the 45 day period the US would "carefully observe North Korea's actions, and act accordingly."

Bush's remarks came despite close ally Japan expressing its unease over North Korea being taken off the US blacklist before the issue of its citizens abducted by the North in the 1970s and 80s is resolved.

On Friday foreign ministers from the G8 industrial powers urged North Korea to maintain its commitment to abandon all its nuclear weapons and to take "prompt action" to resolve the abduction issue with Japan.

The ministers from Britain, Canada, France, Germany, Italy, Japan, Russia and the United States said it was important to verify Thursday's long-awaited declaration submitted by North Korea.

'End these activities'

The removal of North Korea from the US terrorist-sponsor list could ease international trade and financial restrictions, as well as improving ties between Pyongyang and Washington.

The Yongybon plant has been the focus of North Korea's nuclear programme
The US actions would depend on verification of continued North Korean moves towards its nuclear disarmament, Bush said.

"The two actions the United States is taking will have little impact on North Korea's financial and diplomatic isolation ... All United Nations Security Council sanctions will stay in place as well," he said.

"North Korea must dismantle all of its nuclear facilities, give up its separated plutonium, resolve outstanding questions on its highly enriched uranium and proliferation activities, and end these activities in a way that we can fully verify."

The North Korean report delivered to Chinese officials is a truncated version of a declaration originally sought by Washington.

Al Jazeera's correspondent said the report does not appear to answer any questions about the North Koreans' nuclear enrichment programme and does not specifically say how many nuclear warheads they have.

Some critics of the Bush administration say the report is not a full enough disclosure of what the North Koreans have been up to in the past few years and say Washington is not putting enough pressure on Pyongyang.

Officials in the White House however say any sort of development of this kind should be welcomed as a positive move.