Two senior Taliban officials have confirmed the death of leader Mullah Omar, as the group elected a new leader.

The one-eyed cleric, who sheltered Osama bin Laden's Al-Qaeda in the years leading up to the 11 September, 2001, terrorist attacks on the US, had not been seen in public since he fled Afghanistan on a motorbike in 2001 but he remained an important and unifying figure for his followers.

Abdul Hassib Sediqi, spokesman for Afghanistan's National Directorate of Security, said Omar had died in Pakistan in April 2013.

He added: "He was very sick in a Karachi hospital and died suspiciously there."

The Taliban, however, published a biography in April last year which said he was still involved in "jihadi activities".

There have been rumours of Omar's death in the past but this time, as well as the confirmation from the Afghanistan government, the US has also said reports of his demise are "credible".

Omar was born in the southern Uruzgan province in the early 1960s and became a mullah in Kandahar, taking up arms when the former Soviet Union sent troops to Afghanistan in 1979.

He became the Taliban leader in 1989, after the Soviet war ended, and the group took power in 1996.

The seven-member Taliban Shura has chosen a new leader - Mullah Akhtar Mansoor - during a meeting in the Pakistani city of Quetta. Mansoor had been Omar's deputy for the past three years.

Siraj Haqqani, leader of the powerful Haqqani militant faction, will be Mansoor's deputy.

The group made no comment on the death of Omar, however. Pakistan has also made no comment, and has always denied Omar was housed in the country.

It remains to be seen what the group's next move will be - they are believed to be split on continuing the war or negotiating with the Afghan government under president Ashraf Ghani.

Peace talks due to be held between the Afghan government and the Taliban this week have been postponed.

Earlier in July the two groups had their first face-to-face talks in Islamabad.