KABUL/PESHAWAR, Pakistan (Reuters) - The Taliban’s new political leader is expected to join meetings with U.S. officials in Qatar imminently, Taliban sources said on Saturday as the latest round of talks to find ways to end the 17-year Afghan war entered a sixth day.

The peace talks, initially slated for two days, are continuing despite Taliban representatives staging a brief walkout on Friday over differences with U.S. special peace envoy Zalmay Khalilzad.

Two senior Taliban officials in Afghanistan who are privy to the negotiations said momentum was building following Thursday’s appointment of Mullah Abdul Ghani Baradar as the political leader of the hardline Islamist group.

Baradar, released from a prison in Pakistan last year, is expected to fly to Qatar to join the session - a move they believe will be welcomed by a U.S. side keen to talk to senior Taliban figures.

“He is expected to join soon,” one of the senior Taliban officials in Afghanistan said.

The U.S. Embassy in Kabul was not immediately available for comment.

Question marks remain over Baradar’s health, with Taliban officials saying after his release in October that Baradar needed rest before joining the movement’s leadership council.

Baradar, who earlier led the insurgent group’s military operations in southern Afghanistan, was arrested in 2010 by a team from Pakistan and U.S. intelligence agencies.

A co-founder of the movement, he was a close friend of the reclusive former Taliban leader, Mullah Mohammad Omar, who gave him his nom de guerre, “Baradar” or “brother”.

His appointment marks a new push to bring Taliban out of the political and diplomatic shadows, with several other officials being appointed to oversee education, mining and health issues.

Staging near daily attacks against the Western-backed Afghan government and its security forces, the Taliban controls nearly half of Afghanistan and are widely seen as more powerful than at any time since being toppled in the 2001 U.S.-led invasion.

Speaking in Davos, Switzerland, the Afghan president, Ashraf Ghani, said last week that 45,000 members of the country’s security forces had been killed since he took office in the fall of 2014.

When he joins talks, Baradar will be faced with easing U.S. fears over the Taliban’s refusal to cut ties with al-Qaeda - the issue at the core of Friday’s walkout.

One of the key U.S. demands is a guarantees from the Taliban that Afghanistan would not be used as future base for terrorist attacks against the U.S. and its allies.

“The Taliban has assured the U.S. that they will oppose any attempt by militant groups to use Afghanistan to stage terrorist attacks on America or its allies,” a senior Taliban leader told Reuters, adding that U.S. wants the Taliban to snap ties with Islamic State and al Qaeda.

“We are willing to denounce links with Islamic State but we refuse to disconnect ties with al-Qaeda because they accept Taliban supremo Sheikh Haibatullah Akhundzada as their leader too,” the leader told Reuters, on condition of anonymity.