Syrian opposition groups meeting in the Qatari capital have signed an initial agreement to form a united group called the Syrian National Coalition.
Details of the agreement are still being negotiated; a delegate at the talks told reporters they would discuss specifics at meetings on Sunday night.
"An initial deal has been signed. The evening session will be for electing the president of the body and his deputy," Ali Sadreddine al-Bayanouni, a Muslim Brotherhood delegate at the talks, told reporters.
The Syrian National Council - once seen as the leading representative of the opposition but now seen in the West as dominated by out-of-touch exiles - had come under increasing pressure to accept a unity plan.
Al Jazeera's Hashem Ahelbarra, reporting from Doha where the opposition groups were meeting, said on Sunday that the new coalition was crucial because it is expected to go forward to set up the new transitional institutions and how to move forward to topple the regime of President Bashar al-Assad.
They are trying to work out the final details of the agreement, which is how many seats are to be given to the main opposition parties, our correspondent said.
"We have started an open dialogue with our brothers and looked at their initiative," the SNC's new leader George Sabra said earlier in Doha before the coalition formation announcement.
"But we have our own point of view and our own ideas that we plan to put forward."
Sabra said "the SNC is older than ... any other initiative" on the table, adding that no opposition group should be forced under the banner of another.
'Declaration of principles'
Ahmad Ramadan, a senior SNC official, said: "We are being submitted to pressure to accept being part of a new formation, in exchange for international promises but with no guarantees."
Ramadan had suggested it would be "difficult to reach an agreement" on Saturday, but added the meeting may come up with a "declaration of principles" in order not to end in failure.
But Burhan Ghalioun, the former SNC chief, was optimistic before Sunday's developments.
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"The meeting is still on, but there has been real progress. There will be a political agreement for common action, a political body to supervise military action," he said.
The SNC had already twice asked for a postponement of the talks on plans for a broad-based government-in-waiting.
Its counter-proposal envisages the formation of a provisional government pending a general congress of the opposition, according to a document seen by AFP news agency.
The existing plan, inspired by Riad Seif who is reportedly seen by the US administration as a potential new opposition chief, envisages the formation of a transitional government, a military council to oversee rebel groups and a judiciary to operate in rebel-held areas.
In Damascus, Omran al-Zohbi, Syria's information minister, called for a national dialogue, and said the army was fighting to boost the chance for talks.
"The only way to succeed in Syria is to sit down at the table to launch a national dialogue," he said.
"The opposition must accept the choice of dialogue and ... the army, by facing down terrorism, is protecting this dialogue."
On the ground inside Syria, there was no let-up in violence on Saturday. Forces loyal to Assad suffered a new blow as two suicide car bombings struck an officers' club in Deraa, cradle of the nearly 20-month uprising.
The attacks killed 20 soldiers and possibly many more, according to the Syrian Observatory for Human Rights (SOHR), the UK-based watchdog group.
"The two bombings were the result of suicide attacks, carried out by two men who drove vehicles loaded with explosives into the garden a few minutes apart," SOHR's Rami Abdel Rahman said.
State news agency SANA reported that three car bombings killed seven people and wounded many, but did not say they were at a military position.
It also said a car bomb had wounded nine people in the southern Damascus neighbourhood of Daf al-Shawk, while state television said a rocket wounded two girls in the Christian district of George Khoury.
The city of Douma, also near Damascus, was hit by government fighter jets on Saturday. In one of the air raids, a hospital and surrounding buildings were destroyed.
It is believed the hospital was empty before the attack.
Elsewhere, the army retook a stretch of the Damascus-Aleppo highway used to send its reinforcements to main northern battlefields, according to the SOHR.
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Regime forces had "gradually advanced over the past 10 days to regain control of several villages that fell in [early] October to the rebels to the west of the Damascus-Aleppo highway", the SOHR said.
But the army had so far failed to enter the strategic rebel-held town of Maarat al-Numan, where fighting intensified after soldiers in the besieged nearby military base of Wadi Deif received supplies.
The army on Saturday destroyed a ship carrying armed rebels on the Euphrates River in the northeast, SANA said, the first time state media has reported such an incident on the river that runs from Turkey through Syria and Iraq.
Also near Turkey, Kurds backed by militia took control of three northeastern towns in two days after urging pro-government forces to leave, the SOHR said.
It said at least 101 people were killed across Syria on Saturday - 41 soldiers, 34 civilians and 26 fighters.
It says more than 37,000 people have died since the uprising erupted in March 2011, first as a protest movement and then as an armed rebellion after demonstrations were crushed.