The biggest push yet to end the conflict was marked by fiery exchanges on day one Wednesday as the militant groups clashed over President Bashar al-Assad's fate at the UN meeting in Switzerland.

Expectations are very low for a breakthrough at the conference, but diplomats believe that simply bringing the two sides together for the first time is a mark of some progress and could be an important first step.

After a day of formal speeches set to be followed this week by talks involving the two sides, UN leader Ban Ki-moon urged both sides to finally work together at the table.

"The world wants an urgent end to the conflict," Ban said in a closing press conference at the talks in the Swiss town of Montreux on Wednesday. "Enough is enough, the time has to come to negotiate."

But official statements made by the delegations gave no hint of compromise.

Branding the opposition "traitors" and foreign agents, Syrian officials insisted Assad would not give up.

"Assad will not go," Syrian Information Minister Omran al-Zohbi said on the sidelines of the conference.

In his speech, Syrian Foreign Minister Walid Muallem surprised observers with revealing some bitter facts over the support of some western and Arab regimes from terrorist groups in Syria.

He also condemned the foreign backed opposition as traitors.

"They (the opposition) claim to represent the Syrian people. If you want to speak in the name of the Syrian people, you should not be traitors to the Syrian people, agents in the pay of enemies of the Syrian people," Muallem said.

About 40 nations and international bodies were gathered based on US-led policy, but no direct talks are expected until possibly Friday -- when both sides will meet in Geneva for negotiations that officials have said could last seven to 10 days.

NJF/NJF