Rahmat Gul, Associated Press
In this Tuesday, July 7, 2015 file photo, Afghan security forces inspect the site of a suicide attack after clashes with Taliban fighters at the gate of an intelligence facility in Kabul, Afghanistan.

KABUL, Afghanistan — The Afghan Taliban, who have been fighting to topple the Kabul government for almost 14 years, said on Thursday they are "not aware" of a new round of peace talks due the following day in Pakistan — a statement indicating the group may be pulling out of the negotiations.

The apparent rejection of the talks comes a day after Kabul announced the death of the Taliban's reclusive leader Mullah Mohammad Omar, but it was not immediately clear if the two developments were connected.

The Afghan intelligence service asserted Wednesday that Mullah Omar died in a Karachi hospital more than two years ago. In Washington, the U.S. government said they considered the report of the Taliban leader's death credible, though it was not confirmed by the Taliban or Pakistan.

Afghan President Ashraf Ghani's office said Mullah Omar's death would strengthen conditions for the peace process, which has been his priority since he took office last year.

The first round of the official, face-to-face discussions was hosted by Islamabad earlier this month. The meeting was supervised by U.S. and Chinese representatives and ended with both sides agreeing to meet again — a significant progress in itself.

This week, Pakistan announced the second round would take place Friday, in the resort town of Murree. But Thursday's statement from the Taliban, who call themselves the "Islamic Emirate" contradicted that.

"The Islamic Emirate has handed all agency powers in this regard to its Political Office and they are not aware of any such process," the statement said, referring to the talks.

The statement made no mention of Mullah Omar or his reported death.

The Afghan government did not have an immediate comment on the Taliban statement. Ghani's office said he had flown to Germany on Wednesday for unspecified medical treatment. No details of his medical condition were immediately available.

The Taliban have been fighting to overthrow the Kabul government since 2001, when the United States led an invasion to topple its extremist regime.

The allegedly enduring leadership of Mullah Omar, despite numerous past reports of his death, had provided a unifying force both for fighters on the ground and those on both sides who have pushed the peace process forward in the months since Ghani took office.

If confirmed, his removal creates a leadership vacuum in the Taliban, and appears to have exposed rifts at the top of the organization, which is widely believed to be split among those who support and reject contact with Ghani's government.

After the U.S.-led invasion, remnants of the Taliban led by Mullah Omar fled over the border into Pakistan, where they are believed to have the protection of Islamabad. Mullah Omar has not been seen in public since then, though statements have been issued in his name giving credence to Taliban denials of his death.

Most recently, a statement purportedly by Mullah Omar was issued on the occasion of this month's Eid-al-Fitr holiday, expressing support for the peace talks.