Haitham Maleh, a veteran Syrian opposition leader, said discussions with Sabra will continue but the leadership group might be formed without the SNC if an agreement can't be reached.
"If they (SNC representatives) don't accept having a common body, we could form a political body alone," Maleh said.
Damascus has dismissed the meeting in Doha, and Information Minister Omran al-Zoubi called it a political folly. In an interview on state-run Syrian TV aired late Friday, al-Zoubi said those who "meet in hotels" abroad are "deluding themselves" if they think they can overthrow the government.
Syrians, who fled violence and found refuge in neighboring countries, like Turkey, Jordan and Lebanon, urged Sabra and other opposition leaders to work together to end bloodshed.
"Our priority is to stop killing of the Syrian people. They should unite and become a single entity," said Abdulrahman Mostafa, 33, who has been living in the Yayladagi refugee camp in Turkey's Hatay province along the border with Syria. "If our leaders are not united, how can we stand united as a people?"
Hundreds of thousands of Syrians have fled the violence in their country, inundating neighboring countries. As many as 11,000 crossed the borders on Friday, a surge attributed to fighting at Ras al-Ayn in the predominantly Kurdish oil-producing northeastern province of al-Hasaka.
The uprising against Assad began in March 2011 with peaceful protests in Daraa, inspired by the Arab Spring wave of revolutions in the Middle East. But a regime crackdown prompted fierce fighting, propelling the conflict into a civil war that has taken on sectarian overtones. In all, activists say more than 36,000 people have been killed.
The Britain-based Syrian Observatory for Human Rights, which relies on a network of activists on the ground, said two suicide bombers drove their explosives-laden cars into a military encampment behind the officer's club in Daraa in quick succession. It said at least 20 soldiers were killed, most in the second explosion.
Other activists described explosions that targeted the high security area but didn't say they were suicide attacks. State-run news agency SANA reported triple car bombings in Daraa that killed seven civilians and wounded several others.
The government rarely provides death tolls for security forces, and the discrepancy could not be reconciled or independently verified.
There was no immediate claim of responsibility for Saturday's attack, but Jabhat al-Nusra, an al-Qaida-inspired extremist group that is fighting alongside the rebels, has said it was responsible for similar bombings in the past.
In other violence, Syrian TV said a locally made rocket slammed into a four-story residential building in the district of al-Qassaa in the capital of Damascus, wounding two young women.
SANA said three mortar rounds were fired in central Damascus Saturday evening, injuring several people and damaging a clinic in a residential building in al-Tilyani neighborhood.
The state media blamed "terrorists" for the attacks — the term used by the Syrian government to describe rebels.
Surk reported from Beirut. Zeina Karam in Beirut, Mehmet Guzel in Yayladagi, Turkey, and Abdullah Rebhy in Doha contributed to this report.