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 tunnel 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. Al Jazeera's Charles Stratford reports.