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 al-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.
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 channeling 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 around 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 Syrian conflict began with peaceful protests against Assad's autocratic rule that were met with military repression, leading to an armed insurgency.
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.