The first explosion was reported late on Thursday night near a residential area of Spin Boldak.

Witnesses in Chaman, a town three miles across the Pakistani border, described being woken by a loud bang around midnight, and seeing the flare of blasts continue for hours.

The area around Spin Boldak is a former stronghold of the Taleban and Al-Qa’eda. No U.S. forces were reported in the area at the time of the explosions. U.S. forces do maintain a base in Qandahar, about 150 kilometres west of Spin Boldak.

U.S. forces have been combing the area, which borders on Pakistan's tribal areas, for Taleban and Al-Qa’eda, suspected to be behind the 11 September attacks on the United States.

"We have very recently discovered some new stuff that is not old and it is modern", Rumsfeld said in an interview with "The Washington Times" published Friday.

"It is expensive. It is well done. When we raided some places we found - I'm not going to say where - we found backpacks all well done with the right equipment and modern stuff and professionally done. So it's not like the money's dried up. There's still more money and new things coming it", Mr. Rumsfeld added

Ten Pakistan soldiers were killed earlier this week on the Pakistan side of the border in a gun battle with suspected Al-Qa’eda fighters. In response, Pakistan authorities have launched an operation against the group in the area. Pakistan says it has arrested more than 300 Al-Qa’eda or Taleban fighters in the region recently, but officials say there may be as many as 1,000 others still in the area.

At daybreak Mohammed Agha, an Afghan soldier, told Pakistani journalists in Spin Boldak that up to 50 people were missing, possibly buried in the rubble strewn across Spin Boldak that had been showered with rockets and other ammunition from the dump.

It was not immediately clear whom or what had started the explosions.

Fazaludin Agha, the Afghan commander in Spin Boldak, told Pakistani journalists that Al-Qa’eda was responsible though he refused to give more details.

It was not clear if he meant that Osama Ben Laden's fighters had set off the initial explosion or were responsible for storing munitions there in the first place.

Leaflets distributed in Chaman recently warned that the Taleban leader, Mullah Mohammed Omar, was about to launch some form of strike in the area, he said. The scale of the destruction was on a level consistent with an attack.

Khaled Mansour, a spokesman for the UN's World Food Programme in Islamabad, said that a rocket hit the agency's warehouse in Spin Boldak, injuring six people sleeping in houses nearby and starting a fire.

Nine houses and 13 shops in the town were completely destroyed.