More than 20 truckloads of ammunition and weapons were destroyed in the biggest controlled explosion British forces have carried out since World War II. 

After hours of careful preparation, charges were set off simultaneously in all four caves at 4.30p.m. local time on Friday. 

The weapons were found by a reconnaissance brigade of Britain's 45 Commando group -- part of the Royal Marines -- involved in the UK-led mission called Operation Snipe. 

The size of the explosion took even the demolition experts by surprise. 

Eyewitnesses said a 50-foot roar of flame burst from each of the cave entrances, and dozens of jets of tracer bullets shot all over the valley. 

An enormous cloud of smoke and dust rose around 1,000 feet into the air and enveloped the valley, blocking out the sunlight. 

A journalist at the scene said: "We watched from the closest vantage point of one kilometre away, and were still caught by a shower of dirt and earth that lasted 20 seconds." 

The explosions also detonated hidden landmines around the site. Rockets and mortars continued to explode more than an hour after the blast. 

Engineer Lance Corporal James O'Neill, who detonated the explosives, said after the blast: "My first thought was God Almighty. None of us were expecting it to be that big. 

"We didn't really know how it would go. I would certainly say it was a success, although I wouldn't have minded standing a few feet further back.

It gives me great pride to know I've done my little bit to help to stop the terrorists. This is a great morale boost for us all, and what a visual image it was." 

The commandos gave each cave an affectionate name -- Daisy, Amanda, Donna and Jessica -- after wives and daughters back home. 

Almost 200lbs of high explosives were placed inside the cave at eight strategic positions to ensure all the munitions would explode.