Syria's exiled opposition began debating Saturday whether to join international peace talks next week after Damascus offered concessions including a ceasefire plan for the battered city of Aleppo.
But the National Coalition remains riven by internal divisions, making its attendance at the key talks in Switzerland far from certain despite intense pressure from the West and Arab states.
And US Secretary of State John Kerry bluntly dismissed the Damascus regime's proposals as a diversionary ploy ahead of the so-called Geneva II conference, saying "nobody is going to be fooled".
The talks opening Wednesday are aimed at setting up a transitional government to find a way out of the brutal conflict that has killed 130,000 people and made millions homeless since March 2011.
The Coalition's general assembly began meeting at a hotel in a far suburb of Istanbul on Saturday after haggling over various issues prevented the talks beginning as planned on Friday.
The opposition -- an umbrella of myriad groups -- has long struggled to put forward a united front during the war, rocked by infighting over its leadership and efforts to form a government in exile.
And many members are appalled at the idea of sitting down at the same table with representatives of the hated regime they have been trying to unseat for almost three years.
In a surprise move in Moscow on Friday, Syria's Foreign Minister Walid Muallem presented his Russian counterpart Sergei Lavrov with a security plan aimed at halting "all military actions" in the devastated northern city of Aleppo.
Muallem also said the regime was willing to swap prisoners with the rebels in the first such mass exchange since the conflict erupted, while Lavrov said Damascus was ready to take "a series of humanitarian steps" to improve the delivery of aid.
And on Saturday, food aid entered the besieged Yarmuk Palestinian refugee camp in Damascus -- where dozens of people are reported to have died of hunger and lack of medical care -- for the first time in four months.
Syria, Muallem said, would "make every effort to ensure Geneva II is a success and meets the aspirations of the Syrian people and the direct orders of President Bashar al-Assad".
But Kerry warned the regime it could not divert the peace talks away from the aim of installing a new government.
'Important opportunity will be missed'
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"They can bluster, they can protest, they can put out distortions, the bottom line is we are going to Geneva to implement Geneva I, and if Assad doesn't do that he will invite greater response," he said.
Kerry also sought to allay opposition fears that the negotiations would somehow legitimise Assad's regime and leave him in power, saying: "It's not going to happen."
Media reports have suggested that the United States and Britain are threatening to withdraw support from the opposition if it fails to send a delegation.
But factions within the Coalition -- set up in its current form in November 2012 -- are wary of being drawn into a process they fear could result in Assad clinging to power.
"The goal of any political solution must be to install a government of transition that Assad will play no part in," said Coalition spokesman Khaled Saleh.
The Coalition is beset by rivalries between groups backed by either Qatar or Saudi Arabia, while on the ground, more mainstream Islamist factions are battling Al-Qaeda-linked jihadists.
Turkish Foreign Minister Ahmet Davutoglu told reporters that he was engaged in intensive diplomacy to try to ensure the Coalition went to Switzerland.
"If the Syrian opposition refuses to take part in Geneva II, an important opportunity will be missed," a Turkish diplomat said.
Fighting in Syria on Friday had spilled across the Lebanese border, with eight people, including five children, killed when shells fired from Syria rained down on the border town of Arsal, officials said.
UN refugee chief Antonio Guterres, meanwhile, pleaded for the world to ease the massive burden on countries sheltering the millions of refugees and to open their borders to those fleeing the war.
He was speaking at a meeting in Turkey on Friday of regional countries on the refugee crisis after the United Nations launched a massive $6.5-billion appeal for aid.
"For me it is unacceptable to see Syrian refugees drowning, dying in the Mediterranean or pushed back at some borders," he said.