The talks on agreeing a transitional government had been hit by disagreement over whether a transitional government could survive when the Syrian National Coalition President Moaz Alkhatib left in the middle of deliberations, the sources said.
"It seems that there won't be a government unless Sheikh Moaz comes back from Qatar with enough to convince enough members of the coalition that any government they set up will be viable," said one coalition member who did not want to be named.
The talks launched Saturday are the opposition's second bid to form a transitional government, with its credibility at stake as the country slides into sectarian conflict between majority Sunnis and President Bashar Assad's minority Alawite sect.
The Syrian opposition is set for more talks in Paris on Jan. 28, French Foreign Minister Laurent Fabius told radio station Europe 1.
The 70-member coalition, dominated by Islamists and their allies, was formed with Western and Gulf backing in Qatar at the beginning of December. Power struggles among its members have undermining efforts to agree a transitional government.
The United Nations says 60,000 people have been killed in the almost two-year revolt against Assad. A collapse of the country could draw in rival powers in a region where the Sunni-Shiite fault-line has deepened since the Arab Spring revolts began in Tunisia two years ago.
Some coalition members doubt a transitional government is viable yet.
"There is agreement on the need to establish a transitional government but the majority opinion favors not to form it now without secure areas to operate in and enough international support and guarantees for direct recognition," Coalition member Ahmad Ramadan said.
"Otherwise the government will be born paralyzed," he added.Muslim Brotherhood
The Muslim Brotherhood, the only organized force in the Syrian opposition, has made it clear it does not favor a government at present. But opposition sources said the Brotherhood could change its mind if regional powers, especially Turkey and Gulf states, throw their support behind the project.
"Between the military effort and humanitarian and administration needs a transitional government needs up to $40 million a day to operate. There is no point creating a government that cannot meet the aspirations of the revolt," another source said.
Assad's forces massacred over 100 Sunni men, women and children when they overran an opposition-held district in the central city of Homs last week, in the latest in a string of ethnic cleansing of Sunni areas, according to opposition campaigners.
They said the massacre was part of a campaign to secure an open corridor for Alawite forces deployed on hills in Damascus and coastal bases. The Alawites, who have controlled Syria's military and security apparatus since the 1960s, follow an offshoot of Shi'ite Islam and comprise about ten percent of the population.
A few names have emerged as possible contenders for the prime minister job. The best known was that of Riad Hijab, the highest-ranking official to defect since the revolt, who does not enjoy a good relationship with the Brotherhood.
"Hijab was proposed as prime minister today but angry shouts rang immediately that he is a Baathist," said one member, referring to Assad's ruling Baath Party, in which Hijab served for decades.
ISTANBUL (Reuters) -- The head of Syria's opposition coalition has flown to Qatar to secure promises of financial aid for a transitional government in rebel-held areas, sources at negotiations in Istanbul said on Sunday.