UN inspectors are investigating seven alleged chemical weapons attacks in Syria - three of which happened after the 21 August Damascus incident that led to threats of US military action.
Little is known about the latest three alleged attacks, which the Syrian government asked the UN to investigate.
The 21 August attack left hundreds dead; the resulting outcry led Syria to offer up its chemical weapons arsenal.
The UN will vote later on a plan of action to eliminate the stockpile.
Its resolution is expected to incorporate the text of an agreement by the Organisation for the Prohibition of Chemical Weapons (OPCW), whose 41-nation executive council is currently meeting in The Hague to give formal approval to the plan.
The OPCW will be responsible for dealing with Syria's chemical weapons, and has said it will send in its own team of inspectors next Tuesday.
US President Barack Obama said agreement on the issue by UN Security Council members was a "potentially huge victory for the international community".
Meanwhile violence goes on in Syria. Activists said a car bomb killed at least 20 people near a mosque in Rankus, a town north of Damascus, just after Friday prayers.
In a statement, the UN said its current inspection team in Syria is investigating seven allegations of chemical weapons use this year.
The team, led by Ake Sellstrom, arrived in Syria for its second visit on 25 September and hopes to finish its work by Monday 30 September, the statement said.
It is working on a "comprehensive report" into the allegations that it hopes to have finished by late October.
The UN listed the alleged attacks, which all took place this year, as Khan al-Assal on 19 March; Sheikh Maqsoud on 13 April; Saraqeb on 29 April; Ghouta on 21 August; Bahhariya on 22 August; Jobar on 24 August and Ashrafieh Sahnaya on 25 August.
Syria has pushed for the investigation of the three post-21 August incidents.
Its envoy to the United Nations, Bashar Jaafari, accused "militants" of using chemical gas against the army in Bahhariya, Jobar and Ashrafieh Sahnaya.
It was the Ghouta incident of 21 August that sparked international outrage and the threat of military action from the US and its allies.
Since then, Russia - an ally of Syria - has secured an agreement from Damascus to give up its chemical weapons.
Earlier this month, the US and Russia asked the world's chemical weapons watchdog, the OPCW, to decide how to ensure the "complete elimination of all chemical weapons material and equipment" in Syria by the first half of 2014.
The OPCW's text calls for inspections to begin by Tuesday. An advance team will probably arrive on Monday.
The OPCW sets out a deadline that will see the destruction of production and mixing/filling equipment by 1 November 2013 and the complete destruction of all chemical weapons material and equipment in the first half of next year.
Syria is instructed to provide "immediate and unfettered" access to the OPCW's inspectors. If it does not, a meeting of the executive council will be called within 24 hours.
The text also authorises the OPCW to inspect "any other site identified by a State Party as having been involved in the Syrian chemical weapons programme, unless deemed unwarranted by the director general".
This is unchartered waters for the OPCW, which is a small organisation that has never undertaken a job of this size or complexity, the BBC's World Affairs correspondent Paul Adams says. It will need a lot of help and is expected to ask for urgent funding and additional personnel, he adds.
If the text is approved by the OPCW's executive council, it will form part of the UN Security Council resolution, which sets out to govern the whole process.
The resolution includes a warning to all the warring parties in Syria that evidence of non-compliance will trigger measures under Chapter Seven of the UN Charter, which could, but does not necessarily, include force, our correspondent notes.