The Afghan Taliban, for the first time, confirmed that its leader, Mullah Mohammad Omar, died on April 23, 2013, admitting that it deliberately covered up the death of its leader for more than two years.

"Several key members of the supreme leading council of the Islamic Emirate [Taliban] and authentic religious scholars together decided on concealing the tragic news of the passing away of [Mullah Omar]... and keep this secret limited to the very few colleagues who were already informed of this incorrigible loss," the Islamic militant group said, according to BBC.

The Taliban, in a biography of its new leader Mullah Akhtar Mansour released on its website on Monday, said that it kept death of Mullah Omar as a secret because NATO forces had announced withdrawal from Afghanistan at the time, reported Reuters.

"One of the main reasons behind this decision was due to the fact that 2013 was considered the final year of power testing between the mujahideen and foreign invaders (NATO)," the statement said, according to the Guardian.

Mansour has taken over Omar's place as Taliban chief after Afghanistan intelligence recently leaked news about Mullah Omar's death, but Mansour's selection triggered a power struggle within the Taliban as some top Talibani leaders refused to pledge allegiance to him, according to AFP.

Mullah Omar, Afghanistan's de facto head of state during the Taliban regime, died at a Karachi hospital in Pakistan on April 23, 2013.