Big explosion in North Korea three days ago

3.40pm

SEOUL - A huge explosion rocked an area in North Korea near the border with China three days ago and appeared to be much bigger than a train blast that killed 170 people in April, Yonhap news agency reported on Sunday.

"There were rumours that the explosion was much bigger than the one at Ryongchon train station and the United States is showing a big interest as the blast was seen from satellites," Yonhap quoted an unnamed source in Beijing as saying.

The cause had yet to be determined but the source said Washington was not ruling out the possibility that the blast may be linked to a nuclear test.

Yonhap reported that a mushroom cloud up to 4 km (2.5 miles) in diameter was spotted after the blast in remote Yanggang province in the country's far northeast.

The New York Times reported in its Sunday editions that the Bush administration had received recent intelligence reports that some experts believe could indicate North Korea is preparing to conduct its first nuclear weapons test explosion.

South Korean government officials were not immediately available for comment.

Thursday was the 56th anniversary of North Korea's founding. The reclusive communist state often stages extravaganzas and big events to mark important anniversaries.

Train cars exploded at the Ryongchon railway station on April 22, killing 170 and wounding an estimated 1,300. The blast was believed to have been caused by a train loaded with oil and chemicals hitting a power line.

- REUTERS