The UN Security Council will hold an emergency meeting on Sunday night to discuss a massacre in the Syrian town of Houla which left more than 90 people dead.
Diplomats say Britain and France had proposed issuing a press statement condemning the Houla massacre, but Russia told council members it could not agree and wanted to be briefed first by Major General Robert Mood, who is heading the UN observer mission in Syria.
The briefing is currently being arranged, although Russia has called for a council meeting to begin at 7.30pm, UK time (6.30pm GMT).
The UN and other governments have issued statements appearing to hold the Syrian regime of president Bashar Assad responsible.
The Syrian government has denied responsibility for the Houla killings.