Opposition delegates say Tuesday's afternoon session of Syria peace talks was cancelled because of significant differences over the creation of a transitional government.
Members of the Syrian National Coalition's negotiating team said the talks ended early to give the Syrian government a chance to make its proposal about the future of the country within the context of the 2012 Geneva communique.
That document is the basis for the current talks in Geneva and calls for several steps to end the crisis in Syria, including creating a transitional government agreed to by both sides.
Rebels fighting Syrian President Bashar al-Assad insist he must leave power, while the Syrian government says Assad's role is not up for debate at the conference.
On Monday, the government proposed a working paper on Syria's future, which the opposition rejected because it focused on the need to combat terrorism and halt funding and arming of rebels.
In another development Tuesday, an opposition spokesman said the SNC is willing to lift a siege on three pro-government villages in the north of the country as part of a wider agreement to relieve besieged towns on both sides.
Louay al-Safi said Free Syrian Army fighters agreed to relieve pressure on the Shi'ite Muslim villages of Nubl, al-Zahra and al-Foua. But he said Assad's government has not agreed to lift the siege on the rebel-held Old City of Homs, seen as crucial for the success of any deal.
The governor of Homs province said Tuesday a United Nations official is contacting opposition fighters in besieged neighborhoods of the city to allow the evacuation of civilians.
A World Food Program
spokeswoman said U.N. agencies stood ready to truck aid to districts of Homs after a deal at the peace talks, but still needed a green light.
Syria's conflict began in March 2011 as peaceful protests against the government of President Bashar al-Assad before spiraling into a civil war that the U.N. says has killed well over 100,000 people and forced nearly 9 million from their homes.