British marines have discovered what is believed to be the largest al-Qa'ida and Taliban arsenal of the Afghan war, including tanks, artillery and anti-aircraft guns.
The 120 truckloads of arms, stored behind steel doors in a mountain cave complex, were serviced and primed for immediate use, leading to suspicions that the Islamist fighters were preparing for an attack.
The Independent revealed last week that Marines from 45 Commando were told al-Qa'ida and Taliban armour was hidden in the area they had targeted with Operation Snipe in south-east Afghanistan, and an anti-tank troop was brought in.
Members of al-Qa'ida were seen near the four caves, 7,500 feet highin Paktia province, around 10 days ago by villagers, and some of the arms were abandoned outside, indicating they had left in a hurry.
The cache, which also includes mortars and Russian DSHK heavy machine guns, as well as Kalashnikov rifles and ammunition, was in caves around 30ft deep, 9ft wide and 7ft high. They were around 100ft apart and are said to be packed with and linked by tracks for four-wheel drive vehicles.
Yesterday marines entered one of the caves, but found their way blocked by the packed cases of arms and ammunition. One of the caves was damaged by an American air strike leaving potentially unstable ammunition. Army engineers and bomb disposal officers will attempt to make the cave safe before all the stockpiles from other caves can be removed.
The find is the first tangible success of Operation Snipe in which more than 1,000 marines have swept through the highlands and valleys of south-east Afghanistan for more than 10 days. Critics of the mission had claimed that a failure of intelligence had resulted in the biggest British combat deployment taking place in an area from which the enemy had moved out with their weapons.
According to defence sources, part of the problem has been the reliance on information supplied by "Afghan allies" which has proved faulty.
Warlords, especially Padshah Khan in the east, had used the US Air Force to bomb tribal rivals by claiming they were Taliban and al-Qa'ida forces. Senior British officers had sought to avoid similar mistakes by scrutinising allegations from Afghans before taking action.
There was further controversy when the commander of the British force, Brigadier Roger Lane, declared on Wednesday evening that the war in Afghanistan was "all but won", and there was no longer any need for large-scale offensives, despite his troops not firing a shot in anger.
He said that allied offensive missions such as Operation Snipe, which has yet to engage any enemy, were likely to be phased out in weeks rather than months.
The Brigadier also maintained that Snipe has been a success because it has cut through a key al-Qa'ida base and supply line and prevented the enemy from mounting a counter-attack.
Announcing the arms discovery yesterday at Bagram air base, the allied headquarters for the war in Afghanistan, he said: "I think it vindicates Operation Snipe."
Brigadier Lane said the Taliban and al-Qa'ida may have chosen that particular area to hide their weapons because it was regarded as a de-militarised zone by three neighbouring warlords and not under scrutiny. He said: "The caves were used by al-Qa'ida and the Taliban for the storage of a major weapons arsenal.
"We have not yet fully searched these facilities but the inventory includes a wide range of armaments, including anti-aircraft and anti-tank and heavy munitions.
"We've searched a large area, we've found caves and we're then going to destroy that logistic infrastructure.
"I think the operation has been successful in denying them a safe haven."
He added: "As we understand it's a confluence of three particular areas in which warlords have some kind of influence and they're very reluctant to go and press forward too far into that area in case that raises tensions with another one. So it is a vacuum if you like from influence of the warlords."
The US military spokesman Major Bryan Hilferty said that, in a separate operation, 200 anti-tank and anti-personnel mines had been seized by coalition troops south of Gardez, in eastern Afghanistan.