International mediator Kofi Annan said on Friday he was "optimistic" that ministerial crisis talks on Syria's conflict being held on Saturday would produce an acceptable outcome.

But senior envoys who had gathered in Geneva were huddled in private meetings on Friday trying to come up with ways to break the deadlock on Syria's political transition after Russia proposed changes to Annan's plan, diplomats said.

"I think we are going to have a good meeting tomorrow. I am optimistic," the UN-Arab League envoy to Syria told Reuters Television in Geneva as he arrived for preparatory discussions.

The talks being held in the Swiss city by foreign ministers of major powers and regional players will produce "an acceptable result", he said, without giving details.

Russia said on Friday it regretted that Iran, Saudi Arabia, Jordan and Lebanon have not been invited to the meeting of the five permanent members of the UN Security Council on Syria, the Foreign Ministry said in a statement.

The European Union on Friday called for a complete cessation of violence by all parties in Syria.

EU leaders called for an international, transparent, independent and prompt investigation into violations of international law and human rights with a view to ensuring accountability for those responsible.

Reuters-Xinhua