FRAGILE HOPE

"Hope exists but it's fragile. We must continue because the solution to this terrible Syrian conflict is political and needs us to continue discussions," said French Foreign Minister Laurent Fabius. "Obviously when we hear Bashar al-Assad's representative, whose tone is radically different, we know it will be difficult."

Moualem called on foreign powers to stop "supporting terrorism" and to lift sanctions against Damascus.

Referring to rebel acts, he said: "In Syria, the wombs of pregnant women are cut open, the foetuses are killed. Women are raped, dead or alive ... Men are slaughtered in front of their children in the name of the revolution."

He insisted Assad's future was not in question, saying: "Nobody in this world has a right to withdraw legitimacy from a president or government ... other than the Syrians themselves."

US Secretary of State John Kerry echoed the rebel view that there is "no way" Assad can stay under the terms of a 2012 international accord urging an interim coalition. But Lavrov said all sides had a role and condemned "one-sided interpretations" of the 2012 pact.

Saudi Arabia, which backs the Sunni rebels, called for Iran and its Shi'ite Lebanese ally Hezbollah to withdraw forces from Syria. Iran, locked in a sectarian confrontation across the region, was absent, shunned by the opposition and the West for rejecting calls for a transitional government.

Kerry acknowledged Tehran could play a role in a solution. "Iran certainly does have an ability to be helpful and make a difference," he told reporters. "There are plenty of ways that that door can be opened in the next weeks or months, and my hope is they will want to join in a constructive solution."

The conference has raised no great expectations, particularly among Islamist rebels who have branded Western-backed opposition leaders as traitors for even taking part.

HUMANITARIAN CRISIS

U.N. chief Ban opened proceedings by calling for immediate access for humanitarian aid convoys to areas under siege. "Great challenges lie ahead but they are not insurmountable," Ban said, condemning human rights abuses across the board.

But there was little sign of compromise on the central issue of whether Assad, who inherited power from his father 14 years ago, should make way for a government of national unity.

He himself says he could win re-election later this year and his fate has divided Moscow and Washington. Both endorse the conclusions of the 2012 meeting of world powers, known as Geneva 1, but differ on whether it means Assad must go now.

Lavrov repeated Moscow's opposition to "outside players" interfering in Syria's sovereign affairs and prejudging the outcome of talks on forming an interim government. He also said Iran - Assad's main foreign backer - should have a say.

The Kremlin is wary of what it sees as a Western appetite for toppling foreign autocrats that was whetted in Libya in 2011. Moscow opposes making Assad's departure a condition for peace. Speaking of the Geneva Communique, Lavrov said: "The essence of this document is that mutual agreement between the government and opposition should decide the future of Syria."