The gulf between the two sides was on full display at a turbulent morning session in which delegations from the opposition and the Syrian government faced off on the question of Mr. Assad’s future.

The key issue of a transitional government to replace President Bashar Assad blocked any progress on Monday in Syrian peace talks, described by one delegate as “a dialogue of the deaf.”

The chief U.N. mediator expressed frustration over inflammatory public remarks by the two sides as he sought to identify some less-contentious issues in hopes of achieving any progress at all at the bargaining table.

But even the most modest attempts at confidence-building measures faltered including humanitarian aid convoys to besieged parts of the central city of Homs and the release of detainees. Veteran mediator Lakhdar Brahimi sombrely declared at the end of the day that he had little to report.

“There are no miracles here,” Mr. Brahimi said, adding that both sides nevertheless appeared to have the will to continue the discussions. Asked how he planned to bridge the enormous gap between the two sides, the veteran diplomat quipped- “Ideas, I’ll take them with great pleasure.”

The gulf between the two sides was on full display at a turbulent morning session in which the delegations from the opposition and the Syrian government faced off on the question of Mr. Assad’s future.

The Western-backed Syrian National Coalition wants an interim replacement for Mr. Assad, reiterating at every opportunity that the stated goal of the peace conference, agreed upon by international powers in preliminary talks in June, is to establish a transitional government with full executive powers.

But Mr. Assad, whose troops have a tenuous upper hand in Syria, has said he has no intention of stepping down and, on the contrary, may run again for president later this year. His delegates have capitalised on the ascendance of Islamic militants, saying the priority at the peace conference was to find ways to combat terrorism.

“We came here with the intention of discussing a transitional governing body and they came with the intention of consecrating Bashar Assad’s presence,” said Rima Fleihan, a member of the coalition’s negotiating team.

Murhaf Jouejati of the coalition said the meeting ended on a “sour note,” and the session was broken up by Mr. Brahimi after the government delegation became confrontational.

“We thought there was no point in continuing this since it was going to be a dialogue of the deaf,” Mr. Jouejati said.

Despite the rancorous rhetoric outside the conference room, both sides have said they won’t withdraw from the talks.

Mr. Brahimi said the parties were talking to the media “too much,” adding that he asked them to respect the confidentiality of the discussions and avoid exaggerations. Still, all signs pointed to impasse.

White House spokesman Jay Carney said the U.S. was “realistic about how difficult this is going to be, but we are completely convinced that this is the only way forward for Syria, and that’s through negotiations.”

On Sunday, after three days of talks, a tentative agreement was reached for the evacuation of women and children trapped in Homs before aid convoys go in. As of Monday night, there was no progress on the ground.

Mr. Brahimi cited security problems for part of the delay. The opposition delegation has little control over armed groups inside Syria. Fighters affiliated with the Western-backed coalition have been engaged in deadly fighting with al-Qaida-backed militants, who do not accept the coalition’s authority and do not feel bound by agreements reached in Geneva.

The most powerful rebel groups include two that the U.S. has formally designated as foreign terrorist organizations- the Iraqi State of Iraq and the Levant, and Jabhat al-Nusra.

On Monday, talks were supposed to shift to thorny political issues such as Mr. Assad’s future.

As the meeting got underway, the government delegation put forward a paper focusing on the need to combat terrorism and halt funding and shipments of weapons to rebels fighting to topple Mr. Assad, delegates said.

Bouthaina Shaaban, an Assad adviser, called the paper an “expression of good will” in search of common ground, and said she was surprised the opposition rejected it.

“Either these people have no capacity to express their love and care for Syria, or they are ordered by foreign powers to ignore what is most important and most urgent for their country,” she said.

The opposition called the paper a deviation from the talks’ main goal of a transitional government.

The Britain-based Syrian Observatory for Human Rights, which tracks the fighting, estimated that 1,200 women, children and elderly people are trapped in besieged areas of the old quarter of Homs.

The opposition accused authorities of blocking a convoy of 12 trucks trying to get into the embattled city and said, “We will judge the regime by what it does, not by what it says.”

Ms. Shaaban dismissed the aid effort for Homs as a distraction aimed at bolstering the opposition’s credentials.

DPA adds:

Syrian government and opposition delegations are due on Tuesday to resume direct talks after discussions over an interim administration for the war-torn country stalled.

UN and Arab League peace envoy Lakhdar Brahimi has said that the second day of direct talks would again focus on the political framework agreed by talks sponsors the United States and Russia.

Under the so-called Geneva I declaration, the two sides are supposed to negotiate a legal structure for the interim authority, to be comprised of members of President Bashar al-Assad’s government, the opposition and independent figures.

Mr. Brahimi on Sunday announced that the government had agreed to evacuate women, children and the elderly trapped in the rebel holdout of Homs, which has been under siege from government forces since July 2013.

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