KANDAHAR, Afghanistan - Sarposa prison is only 40 years old, but walking through the wing that houses criminal and political prisoners is like stepping back in time.

The light is dim, the ceiling is low and the maximum-security inmates -- they move around freely during the day in long, stone-lined corridors behind heavy steel doors -- are surprisingly quiet, whispering to themselves and avoiding eye contact.

Daylight, the only proof that the sun is up outside, streams through the door in narrow beams via myriad bullet holes -- a reminder of the stunning siege in June 2008, when insurgents staged one of their most brazen and successful attacks.

They freed more than 1,000 inmates, including an estimated 400 Taliban, and killed at least a dozen guards -- including the prison director's son and nephew, both of whom were standing by the front gate when the attackers blew up a pair of tanker trucks packed with explosives.

"I have very dangerous prisoners," Col. Abdullah Khan Bawar boasts as he leads a tour of the facility.

"They are suiciders, they are people who were planting IEDs and I have Taliban commanders and political prisoners -- very dangerous guys at this prison."

Nor, it would appear, are they completely powerless while in prison, Bawar conceded.

"I found a cellphone a couple of days ago. It was one of the political inmates, and he had contacted Pakistan and inside the country -- he talked to people and he texted people and we caught him."

The number of inmates continues to grow at Sarposa -- the total is 841, including 449 criminal, 318 political, 89 young adults and 15 women, along with 12 children in the newly renovated women's wing.

Another wing for juveniles has been rebuilt but remains empty.

"Business is booming, I see," said Gail Latouche, the Corrections Canada officer overseeing the renovations at the prison and the chief mentor for the guards, during a recent unannounced visit.

Latouche, who spent 14 years of her career guarding prisoners at Stony Mountain Institution in Manitoba, is part of the team of Canadians who are helping to bring notorious Sarposa back up to standard.

Within days of the assault last June, the federal government announced an additional $4 million for the reconstruction of the prison, with up to half of the money earmarked specifically for urgent repairs resulting from the attack.

There has been visible progress. The juvenile wing and guard towers are complete, as are renovations to the women's ward and the outside wall. The administrative offices and work outside the front gate are not yet finished.

Allegations that political prisoners -- those accused of links to the Taliban -- were tortured at Sarposa at the hands of Afghan security forces are ancient history, said Latouche, whose teams train guards on everything from human rights and UN standards to the basics like first aid, arrest and control and the handling of weapons.

"I'd say there's a marked improvement the more time we are there," she said. "This is one of the success stories."

In case some of the guards should forget their training, there's a sign on the wall near the front gate, written in Pashto, that offers pointed reminders -- things like, "Ignorance of the law is not an excuse," "Everyone has the right to defence counsel," and "Torture is forbidden."

"I am abiding the rules," Bawar said. "We are obeying human rights."

His prisoners, he added, "are actually happy." They also know what happens if they get out of line: a one way ticket to Pul-e Charkhi in Kabul, "one of the hardest prisons in the country."

Latouche said the more time she spends at the prison, the more it seems like those she knows well back in Canada. But it's a challenge, she acknowledged -- many of the guards are unable to read or write and have different views of how things should be handled.

"We were training arrest and control and talking with this new recruit class, and said, `What would you do if the warden asked you to bring one of the inmates to his office to have a discussion and the inmate refused to go?"' she said.

"The officer said, 'Well, I'd probably have to shoot him.' So that's our reality. He's actually quite a good officer right now."

The prison is under constant threat of attack by the Taliban, said Bawar, who knows his enemies are in close proximity -- just two football fields away from the facility's six-metre high stone walls, topped with razor-sharp barbed wire.

"We receive two or three reports a week from the (National Directorate of Security) that our enemies are trying to attack," he said.

"If the enemy wants to attack the prison we're always ready. They have not reached their purpose."