Huge blast in North Korea fuels nuclear bomb fears

North Korea may have brazenly defied the rest of the world by carrying out tests linked to the production of a nuclear bomb last week during celebrations to mark the 56th anniversary of the state's foundation.

North Korea may have brazenly defied the rest of the world by carrying out tests linked to the production of a nuclear bomb last week during celebrations to mark the 56th anniversary of the state's foundation.

A huge explosion rocked a remote part of North Korea last week, it was reported in the South Korean capital, Seoul, yesterday. American and South Korean officials rushed to say that despite the appearance of a "peculiar cloud" over the area, it was unlikely to have been a nuclear weapons test.

The news came during a visit to the North Korean capital by Bill Rammell, a British Foreign Office minister, who learnt of the explosion, 250 miles north of Pyongyang, just after 1pm while at the British ambassador's residence. He informed officials at the North Korean Foreign Ministry, who were apparently unaware of the reported explosion.

Mr Rammell, who hopes to receive details today from the North Korean Foreign Minister, Paek Nam Sun, said the incident highlighted "the difficulties that we have with them in their dealings with the outside world".

The first report, from the South Korean news agency Yonhap, said that "a mushroom cloud with a radius of 3.5 to 4km was spotted in Kimhyongjik county" on Thursday, the 56th anniversary of the establishment of North Korea. The mountainous area is closed to foreigners. Diplomats said that the location of North Korea's nuclear test site is unknown.

Some Korea watchers had feared that North Korea might carry out such an act as the temperature rises again in its dispute with the Americans over Pyongyang's suspected nuclear weapons programme.

But as the hours wore on, other possible explanations surfaced for the cloud. It may have been caused by an exploding rocket, or by a massive forest fire. The Americans were quick to deny that any nuclear explosion had taken place.

One diplomatic source in Pyongyang noted that the report surfaced in South Korea. "It may have been a fishing expedition by the South Korean press perhaps. It happens all the time." Diplomats were also puzzled as to why North Korea would risk alienating China, almost its only remaining ally, by exploding a bomb on its border with all the risks to the Chinese population that it would entail.

It was also unclear why North Korea would have taken the risk of exploding a bomb in the atmosphere, with the possibility of long-term loss of life to its own citizens.

If it was a nuclear bomb test there is likely to be fallout in Washington, which failed to predict the 1998 tests by Pakistan which led to a series of tit-for-tat explosions by India and Pakistan and brought the two countries to the brink of war.