Talks by Syria's opposition to choose a new leadership before an international peace conference stalled on Sunday over proposals to lessen Qatar's influence on the rebel forces, opposition sources said.
The disarray in the opposition ranks emerged as the Syrian foreign minister said President Bashar Assad's government would take part "in principle" in the conference, which could take place in the next few weeks in Geneva.
The U.S. and Russian foreign ministers, who are trying to revive a plan for a political transition in Syria, were due to meet in Paris on Monday to work out the details.
Russia's Foreign Ministry on Friday said the prospects of an international peace conference on Syria being held in Moscow before the end of May looked slim because of the Syrian opposition's stubborn stance.
Alexander Lukashevich, the ministry's spokesman, accused the Syrian opposition of making unreasonable demands that "dilute" the effectiveness of the conference and go against the previous decisions on Syria made by the Action Group of Syria in Geneva on June 30 last year.
"From the very beginning we have been talking about the futility of setting any artificial timeframes for holding the conference," Lukashevich said in a briefing. "Judging by the events that are taking place among the opposition that possibility is hardly realistic."
The opposition's demands include the removal of President Bashar Assad, which Moscow has been vehemently opposing, and the creation of "some sort of government under the UN auspices," he said.
Holding the conference before the end of May was the initial goal set during the U.S. Secretary of State John Kerry's visit to Moscow at the start of the month.
With Iranian-backed Hezbollah militants now openly fighting alongside government troops in Syria, the Saudi monarchy is keen to play a greater role in backing the Sunni-led opposition, the sources said.
Qatar had agreed to let Saudi Arabia play the primary role in opposition politics and the kingdom is expected to lead Gulf efforts to back a new provisional government financially, opposition sources said.
But Mustafa al-Sabbagh, the Qatari-backed secretary general of the Syrian National Coalition who has played a main role in channelling money for aid and military supplies inside Syria, is resisting a Saudi-supported plan to add members to the 60-strong coalition, the sources said.
The coalition is controlled by the Sabbagh faction and a bloc largely influenced by the Muslim Brotherhood, which led resistance to the rule of Assad's late father in the 1980s, when many thousands of Brotherhood members and leftists were executed and tortured.
Relations between Saudi Arabia and the Muslim Brotherhood improved after a senior Brotherhood official met Saudi officials in Riyadh earlier this month.
"Sabbagh has been told by Qatar that the Saudis are brothers and he should compromise. But he is a Syrian first and he will put the interest of the national opposition above everything," an ally of Sabbagh in the coalition said.
For the last three days, the coalition has been debating a plan to add 25 members of a liberal grouping headed by veteran opposition figure Michel Kilo.
Ten other members associated with the rebel Free Syrian Army could be also added.
"The mechanism on how to add the new members has not yet been worked out. The outcome of the meeting is still hanging in the balance," another coalition member said.
If the expansion goes ahead, the coalition will move to discuss the Geneva conference and a new leadership, including the fate of provisional prime minister Ghassan Hitto, who has not been able to form a provisional government since being appointed on March 19.
The coalition has been rudderless since the resignation of Moaz AlKhatib, a cleric, who had floated two initiatives for Assad to leave power peacefully.
Washington has pressured the coalition to resolve its divisions and to expand to include more liberals to counter Islamists from dominating the coalition.
The civil war in Syria between the government and various opposition factions has been going on since March 2011. At least 80,000 people on all sides have died during that period.
The war has developed into a sectarian conflict pitting members of Assad's Alawite sect, an offshoot of Shi'ite Islam that has controlled Syria since the 1960s, against members of the Sunni majority.
Material from The Moscow Times has been included in this report.