The meeting of the Syrian Constitutional Committee stalled on Monday as the regime delegation left on the first day of the second round of talks.
The regime delegation proposed three new items on the agenda and left when they were not accepted by some representatives of local NGOs, it was learned.
The Syrian Constitutional Committee -- comprising opposition, civil society, and regime members -- began its work on Nov. 20 in Geneva with the UN facilitation.
The committee is mandated within the context of a UN-facilitated Geneva process, to prepare and draft for popular approval of constitutional reforms paving the way for a political settlement in Syria.
Opposition spokesman Yahya Al-Aridi told reporters that the meeting was called off.
"There is no agreement on the program, on the schedule to be discussed at the meeting," he said.
Aridi said the regime delegation wanted to discuss fighting terrorism, lifting of sanctions and condemnation of Turkey's operation in northern Syria.
He said the Adana agreement signed in 1998 between Turkey and Syria was clear on the operation.
Turkish President Recep Tayyip Erdogan maintains the agreement allows Turkish forces to conduct operations inside Syria near the Turkish border.
Aridi also said : "What was presented [by the regime] was something merely political."
Aridi added that regime attacks in Syria's Idlib may have the goal of harming the works of Constitutional Committee.
Syria has been locked in a vicious civil war since early 2011, when the Bashar al-Assad regime cracked down on pro-democracy protests with unexpected ferocity.
Since then, over 5 million civilians have become refugees. Turkey hosts 3.6 million of them, more than any country in the world.
* Writing by Fatih Hafiz Mehmet in Ankara