By Darya Korsunskaya
SOCHI, Russia, May 17 (Reuters) - A proposed international conference on Syria should be held as soon as possible, U.N. Secretary-General Ban Ki-moon said on Friday, but no date has yet been agreed for a meeting that appears to face growing obstacles.
Ban spoke as U.N. officials announced that the number of refugees fleeing the fighting in Syria, a conflict that has claimed the lives of 80,000 people over the past two years, had exceeded 1.5 million as conditions there deteriorate rapidly.
Western leaders have been cautious about the prospects of the talks achieving any breakthrough, and Russia's desire that Iran should attend could complicate matters because of potential opposition from the West. The main Syrian opposition, expected to decide its stance next week, has previously demanded President Bashar al-Assad's exit before any talks.
A rising death toll, new reports of atrocities by both sides, suspicion that chemical arms may have been used and the absence of prospects for a military solution have all pushed Washington and Moscow to agree to convene the conference.
"We should not lose the momentum," Ban said of the proposal to bring the Syrian government and opposition representatives to the conference table.
"There is a high expectation that this meeting should be held as soon as possible," he said after talks with Russian Foreign Minister Sergei Lavrov.
Lavrov agreed: "The sooner the better," he told a joint news conference with Ban, who was due to meet President Vladimir Putin later on Friday.
Iran is a U.S. foe and the main regional ally of Assad's government, which has also received crucial support from Russia.
"Moscow proceeds from the position that all the neighbouring countries, Iran and Saudi Arabia, and the participants of the first Geneva conference, must be invited," Lavrov said, referring to an international meeting on Syria held last June.
Last year's Geneva talks produced an agreement that a transitional government should be created in Syria, but the United States and Russia disagreed over whether that meant Assad must leave power.
Moscow says his exit must not be a precondition for a political solution, but most Syrian opposition figures have ruled out talks unless Assad and his inner circle are excluded from any future transitional government.
Lavrov said opposition participation would be crucial.
"The main thing now is to understand who, from the Syrian sides, is ready to take part in this conference - without that, nothing will happen at all," he said.
"And the second task is to determine the circle of participants from other countries in addition to Syria."
In remarks published on Thursday, Lavrov said the West wanted to restrict the number of external participants in the conference, which could predetermine its outcome.
The United States said on Thursday that it was not ruling anyone in or out of the conference, while France voiced opposition to Iranian participation.
President Barack Obama said he reserved the right to resort to both diplomatic and military options to pressure Assad but U.S. action alone would not be enough to resolve the crisis.
Russia, with China, has opposed sanctions against Syria and blocked three Western-backed U.N. Security Council resolutions aimed to increase pressure on Assad during the conflict, which began in March 2011 with a crackdown on protests.
U.S. media reported that Russia had deployed naval ships to the eastern Mediterranean off Syria and also sent advanced missiles in a show of support for Assad.
Russia had sent a dozen or more warships to patrol waters near its naval base in the Syrian port of Tartus, a military outpost that gives Moscow a toehold in the Middle East, the wall Street Journal reported.
The New York Times said Russia had sent advance Yakhonts cruise missiles to Syria, which give the government a formidable weapon to deter foreign forces from any intervention. (Reporting by Darya Korsunskaya; Writing by Steve Gutterman; Editing by Giles Elgood and Peter Graff)