US, French and British diplomats were meeting before then to continue discussions on a possible draft UN Security Council resolution.
An initial French draft called for giving the government of Syrian President Bashar al-Assad an ultimatum to give up its chemical arsenal or face punitive measures, a text that Russia has said is unacceptable.
Diplomats said there have been other drafts under discussion and an attempt was being made to come up with common language agreeable to all three Western powers.
"I think we'll come to an agreement," a diplomat from one of the three told Reuters on condition of anonymity.
Later, the French, Americans and British envoys will join Russian and Chinese diplomats for a meeting of all five veto-wielding council members.
"I understand they will be discussing general principles of plans to deal with Syria's chemical weapons," a diplomat said on condition of anonymity. "They (the full five) won't really be discussing draft resolutions yet."
The meeting comes a day before US Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov meet in Geneva to discuss ways of breaking the deadlock on the 15-nation Security Council over Syria. Russia, backed by China, has vetoed three resolutions condemning Assad's government and threatening it with sanctions.
Syria on Tuesday accepted a Russian proposal to surrender its chemical weapons in order to win a possible reprieve from US military strikes that US President Barack Obama has floated as a way of preventing a repeat of a chemical weapon attack on Aug. 21 that killed more than 1,400 people.
Washington and other Western powers blame Assad's forces for the attack. Damascus blames it on the rebels.
Russia has said it does not want a binding Security Council resolution on its Syria proposal but a "presidential statement," a council declaration that Western diplomats would say would not have legal force the way a resolution could.
Western diplomats say a presidential statement would be insufficient and a resolution is necessary.
