Supreme leader of the Afghan Taliban Mullah Mohammed Omar died in Pakistan two years ago, Afghanistan's intelligence agency said on Wednesday.

"Based on credible information, the NDS has confirmed that Taliban leader Omar has died in a mysterious way in a hospital in Pakistan's Karachi two year and four months ago," spokesperson for the National Directorate of Security (NDS) Hassib Seddiqi told Xinhua.

"We are happy that now the foreign sources have also confirmed that Mullah Omar is no more alive. We still have a lot of questions how Mullah Omar died," he told BBC's Pashto service, according to Reuters. "We have been told that the Taliban leader died owing to an illness," he further added.

The office of Afghan President Ashraf Ghani also confirmed the death of Mullah Omar, citing "credible information." Sayed Zafar Hashemi, deputy spokesman for the Afghan President, also confirmed the news on his Twitter account.

Taliban leader's sudden death announcement has triggered a rush within the militant outfit to elect a new leader, security sources told Anadolu Agency. The Taliban on Tuesday held a meeting to choose between Mullah Omar's son Yaqoob and the current acting leader Mullah Akhtar Mansoor

"They are going to hold another meeting in Karachi on July 31, but it is possible [Pakistan's intelligence agency] ISI will disrupt the meeting. On the other side, Mullah Akhtar Mansoor, who has nominated himself for the position is to hold a meeting with the support of ISI in Quetta tomorrow," former Afghan diplomat Ahmed Saedi told Anadolu Agency.

The Taliban and Afghanistan recently initiated peace talks. The Afghanistan government, in a statement, called "all armed opposition groups to seize the opportunity and join the peace process," according to BBC.

The reclusive one-eyed Taliban chief Mullah Omar was Afghanistan's de facto head of state from 1996 to 2001 during Taliban rule. He went into hiding following the U.S.-led invasion of Afghanistan.

The reports of his death have appeared in media several times in past. #MullahOmar started trending on Twitter immediately after the reports about the death of the Taliban leader hit headlines. Here are few reactions on Twitter: