A UN draft discussion paper includes eight “framework principles” to be embraced by all countries and rebel groups that sign on to a ceasefire.
The ceasefire plan also lists issues still to be negotiated, including defining “those terrorist organisations against whom combat is allowed”.
The paper’s authenticity was confirmed by two diplomats who spoke on condition of anonymity.
The diplomats stressed that the document was a draft, originally prepared by the United Nations, and they said multiple versions of the draft have been passed back and forth among US, UN, and other diplomats.
The ceasefire idea, endorsed by the UN Security Council on December 18 at the urging of major powers and regional players that include the United States, Russia, Iran and Turkey, would exclude militant groups such as Islamic State, also known as ISIS, and al-Qaeda affiliated Nusra Front.
Diplomats say the result could be a messy, partial ceasefire in which government and acceptable rebel forces stop shooting at one another but still go after IS militants and other groups branded as terrorist.
With Nusra Front fighters scattered across northern Syria rather than concentrated in any one place, attacks on them could harm civilians as well as groups who signed on to any ceasefire, diplomats and analysts said.
Identifying the groups still subject to attack is a diplomatic task delegated to Jordan’s government.
Staffan de Mistura, the third UN envoy tasked with ending a civil war that has killed at least 250,000 people and driven millions from their homes, has taken the lead in laying out the possible dimensions of a ceasefire, diplomats said.
De Mistura has said he hopes to open talks between the Syrian President Bashar al-Assad’s government and opposition groups in Geneva on January 25.
Those talks will focus on trying to get the two sides to agree on a political transition for Syria.
Separate talks are under way about the shape of a ceasefire and the draft document obtained by Reuters addresses this.
Quick agreement seems likely on some framework principles, such as a recognition of Syria’s territorial integrity, but others will be vexing. Among these is one to require the withdrawal of “foreign fighters unlawfully present in Syria.”