Some 540 members of the Taliban including military commanders have escaped from Kandahar prison via a 320 metre-long tunnel, Afghan government officials have confirmed to Al Jazeera.
A Taliban official on Monday also confirmed the overnight escape, boasting that the prison break had been "very well-planned" and that it was five months in the making, Al Jazeera's Qais Azimy, reporting from Kabul, said.
According to a Taliban statement, the tunnel was not dug by the inmates but by fighters outside the prison.
"Mujahideen started digging a 320 metre-long to the prison from the south side, which was completed after a five-month period, bypassing check posts and the Kandahar-Herat main highway, leading directly to the political prison," the statement read.
"The tunnel reached its target last night, from where the prisoner Mujahideen were led away through the escape route by three previously informed inmates in a period of four-and-a-half hours, starting from 11pm last night and ending at 3:30am this morning. Mujahideen later on sent vehicles to the inmates who were led away to secure destinations."
"They all have made it safe to our centres and there was no fighting," Yousuf Ahmadi, a Taliban spokesman, said.
Ahmadi said that 106 were Taliban commanders while the rest were foot soldiers. Kandahar police said they had re-captured eight commanders so far.
The Taliban said prison guards did not notice the escape until four hours after the operation was completed.
The prison in southern Afghanistan typically holds drug dealers as well as Taliban fighters captured by NATO forces, our correspondent said.
The break constitutes a "big success" for the Taliban and would "have a dramatic effect on the fight against the Taliban in the region," said Azimy.
There have been previous escapes from this prison. In June 2008, Taliban fighters attacked the facility, blasting through its entrance and engaging in a gun battle with police.
Nearly all of the estimated 1,150 prisoners, including some 400 Taliban, escaped, according to Afghan officials.
A Taliban spokesperson said that two suicide bombers blew themselves up near the entrance of the gate to the prison before 30 Taliban fighters attacked and killed 16 policemen.
Kandahar prison was also the scene of a mass hunger strike by hundreds of inmates in May 2008 during which 47 inmates sewed their lips shut after complaining they had been tortured and denied fair trials.
Kandahar city and the surrounding province, considered the birthplace of the Taliban movement, has been the scene of some of the worst fighting in Afghanistan.