Taliban factions disagree on whether to pursue the peace process, particularly as the group has lost local commanders to Isis (Islamic State).
The group's fighters have had battlefield success against the Afghan Army in the more than two years since Omar's death, but the confirmation of his demise may prompt a pullback from peace discussions until new leadership is officially in place and internal disputes are resolved.
"The absence of Mullah Omar is further splintering the Taliban, and that's bad news for peace talks," said a senior analyst at the International Crisis Group in Kabul, Graeme Smith.
"Kabul wants to negotiate with a single large opponent, and trying to haggle out deals with smaller factions would be harder. It's also opening the door for other militant groups, such as self-declared Islamic State factions, which are less willing to negotiate."
The Taliban are planning to formally announce the death of Omar and declare his son Mohammad Yaqub as his successor and the organisation's leader, a Taliban commander in the nation's southern Helmand province, Mullah Akhtar Mohammad, said yesterday.
Omar's deputy, Akhtar Mohammad Mansoor, opposes the family succession because the son has not supported recent peace talks with the Government, the commander said. Omar's deputy did endorse the talks, he said.
The first formal discussions between the Taliban and the Afghan Government since 2001 occurred in the Pakistani hill town of Murree early this month.
They raised hopes for a political solution to a conflict that has killed almost 100,000 people since 2001.
The involvement of Pakistan, which has close ties with the Taliban leadership, appeared to signal a new level of seriousness to peace efforts.
