KABUL/PESHAWAR, Pakistan (Reuters) - Representatives of Afghanistan, China, Pakistan and the United States will meet in Oman next week to discuss reviving peace talks with Afghan Taliban militants, an Afghan official and a Pakistani foreign ministry source said on Wednesday.

But it was not clear if Afghan Taliban representatives would join the talks. Taliban sources said they had not yet received an invitation and plan to skip Monday’s discussions in Muscat, casting doubt on efforts to revive long-stalled negotiations.

The four-nation Quadrilateral Coordination Group (QGC), comprising Afghanistan, China, Pakistan and the United States, has been trying to ease the path to direct talks between the Afghan government and the Taliban, with little success.

The Taliban, ousted in a U.S.-led military intervention in 2001, has been gaining territory in recent years through a violent insurgency to try to topple Afghanistan’s Western-backed government and re-establish a fundamentalist Islamic regime.

Amin Waqad, a close aide to Agfhan President Ashraf Ghani and a senior member of the High Peace Council (HPC), said, “HPC and government representatives will participate, and it is an important one because the Taliban representatives will be there. We will go with a clear plan.”

A senior Pakistani foreign ministry official confirmed the talks would take place on Oct 16. Last week, Foreign Minister Khawaja Asif told Voice of America the “quadrilateral arrangement will again be in operation” in Muscat in October.

The U.S. embassy in Islamabad did not comment for the report.

Talks and efforts to kick start negotiations have failed following the 2015 announcement of the death of the Taliban’s founder and long-time leader, Mullah Mohammed Omar, in 2013.

The United States wants Pakistan, which it accuses of harboring Afghan Taliban commanders, to exert more influence on the group to bring them to the negotiating table.

Pakistani officials deny sheltering Taliban militants and say their influence on the group has waned.

Two senior Afghan Taliban leaders, speaking on condition of anonymity, told Reuters the group’s leadership council met on Tuesday and decided it would not send a delegation to Muscat even if the group was invited to participate.

“Till that time, we were not invited, but even if we received any invitation, our senior members decided not to participate in the meeting,” said one of the Taliban leaders.