Officials at Afghanistan's Kandahar prison show the tunnel through which 480 prisoners, including Taliban commanders, escaped Reuters

Kandahar's prison may not be Stalag Luft III but in terms of ingenuity, organisation and sheer cunning the successful break-out by at least 480 Taliban prisoners in the early hours of Monday morning rivals anything pulled off by British POWs in the infamous German prison camp.

According to people involved in the break-out, the Taliban's great escape began with a team of 18 insurgents on the outside spending five months burrowing hundreds of metres underground through the brown soil west of Kandahar city and into Sarpoza prison, taking their tunnel right into the prison's political section where hundreds of Taliban were held.

As the great escape was a break-in rather than a break-out, there was no need to surreptitiously get rid of the earth inside the camp; according to one local media report, the Kandahar plotters simply sold lorry loads of the earth in the city's bazaar from a tunnel stretching a reported 320 metres.

The starting point was a compound directly opposite the prison that from the outside looked like any one of hundreds of building companies that have popped up in areas awash with reconstruction dollars.

But the metal and concrete beams made there were not for building US-sponsored projects. Instead they were used to support a part of the tunnel that went directly underneath a section of Afghanistan's most important road: the stretch of Highway One running between the cities of Kandahar and Herat.

According to one of the escapees (whose numbers could dramatically tip the odds in favour of the insurgents on the eve of this year's "fighting season"), the tunnel was of sufficient diameter and high enough for the prisoners to stand upright for most of their walk to freedom.

Sections were lit by electric light and ventilated with fans, he said.

One official who visited the prison said the tunnel had two exits, and that the second branch led to a wing of the prison housing ordinary criminals. For whatever reason, that equally grand escape did not come off.

"I only found out that we were going to escape at midnight," the 28-year-old insurgent, who did not give his name, said during a phone interview with the Guardian.

The man, who had served three years of five-year sentence for fighting foreign forces in Afghanistan, said that a mere 20 minutes later he and his cellmates were taken to the entrance of the tunnel, a hole in the concrete floor that dropped down five feet to the tunnel passage itself.

"It was very well organised. They only let a certain number of people go through at one time, because they wanted to make sure there was enough air to breath in the tunnel."

When the escapee prisoners got to the construction company compound at the end of the tunnel, they were met by their commanders and taken off in cars to safe locations.

And to compound the humiliation of the Afghan government and its Nato allies, the prison managers appear to have been totally unaware of the escape until long after the prisoners had disappeared into the night.

From about 11pm to 3.30am, cell after cell of prisoners trooped through the passageway to freedom.

The unfortunate guard who came into the wing first thing on Monday morning was confronted with an entirely empty building, save for prison clothes, shoes and turbans that the inmates had for some reason left behind.

Suspicions were immediately roused that the escape plot must have enjoyed support and help from prison guards to suceed, but the Taliban escaper doubted it. "They were just sleeping," he said amidst extended laughter.

"The guards are always drunk. Either they smoke heroin or marijuana, and then they just fall asleep. During the whole process no one checked, there was no patrols, no shooting or anything."

In a country brimming with every conceivable type of surveillance, security was also assured by the fact that the escape plot was kept secret and was known only to a handful of the prisoners held in the large building divided up into individual, unlocked cells.

"We knew there were informers in our wing, but they did not know anything until it was time to leave," he said.

President Hamid Karzai's official spokesman's description of the mass breakout as a "disaster" seemed entirely accurate.

Not only has it handed insurgents a spectacular propaganda coup, it has also highlighted the continued feebleness of the Afghan government and the enduring strength of the militants, undermining a narrative promoted by Nato in recent months that it has been making progress in the nearly 10-year war.

That government feebleness comes despite the billions of dollars being spent this year to improve the Afghan army and police, not least in Sarpoza. The prison was given an overhaul after the Taliban succeeded in releasing prisoners in June 2008, when insurgents attacked the compound, blowing up a section of wall and freeing 870 inmates, including 390 insurgents.

The display of the Taliban's strength comes after a conventional troop surge and a winter of intensive battering by special forces.

Despite the killing and capturing of huge numbers of Taliban commanders, the movement flaunted its undimmed organisational powers, not least with a sophisticated media campaign which saw a press release in near flawless English being sent out to international media.

It crowed: "The most astonishing thing throughout the operation, as reported by Mujahideen informants, was that all the enemy forces inside the prison, which includes foreign invaders, did not notice the results of the operation even four hours later and hence has not released any statements."

It added that a "martyrdom-seeking group" on standby near the prison were left with nothing to do "due to the inaction shown by the enemy".

The prison break also comes just weeks after a Taliban suicide bomber succeeded in blowing up Kandahar's police chief, and another came close to killing Afghanistan's defence chief in the heart of his sprawling ministry in Kabul.

The bigger question will be how great an effect the break-out will have on the struggle for Kandahar province and the rest of Afghanistan's turbulent south in the critical months to come, the traditional summer "fighting season".

The aftermath of the 2008 prison break does not augur well. That episode led to an instant deterioration in security in the districts around Kandahar city, with battles erupting within days of the escape between the emboldened insurgents and Nato forces.

The tide only seemed to turn against the insurgents in those districts with the coming of the US troop surge last year.

The infusion of experienced, but relatively fresh, Taliban fighters could be a boost to the insurgent campaign. However, this time round there is a much larger presence of US soldiers in the south compared with three years ago when an overstretched Canadian force struggled to keep control in the Taliban's home province.

Generally the inmates in the prison are not the senior Taliban members; the most important insurgents are generally sent to Bagram north in Kabul for detention.

Tooryalai Wesa, the governor of Kandahar, conceded that security forces had "failed in their duty".

He said that strenuous efforts were underway to recapture prisoners, a task he said would be made easier by the fact that all of their biometric data is on record, including fingerprints and iris scans.

"Some of the escaped prisoners have been recaptured by the security forces during search operations, and huge operations have launched inside and on outskirts of Kandahar city for the rest of them," he said.

He also appealed to Kandahar residents to phone in tip-offs about the escaped prisoners to a hotline set up by authorities.

But for the Taliban escapee enjoying freedom for the first time in three years, an experience he compared to the Islamic festival of Eid, there was a belief that the government would not recover from its display of ineptitude.

"We had the full support of the people of Kandahar, who provided us with clothes and safe places to go," he said.

"We have proved that whatever we want to do in Kandahar or anywhere else in the country, we can do it."