The opposition National Coalition said Friday it will form a government to run "liberated areas" of Syria, as monitors said more than 12 people were killed when buildings collapsed in a missile strike on the city of Aleppo.
International peace envoy Lakhdar Brahimi, meanwhile, said a devastating bomb blast in Damascus on Thursday was a "war crime" which had left about 100 people dead.
"We agreed to form a government to run the affairs of liberated areas," Coalition spokesman Walid al-Bunni said after a meeting in Cairo, adding the opposition will meet on March 2 to decide on the composition of the government and choose its head.
Coalition members said the meeting would be held in Istanbul, while Bunni said it was hoped the government would be based in rebel-held territory of northern Syria.
The opposition umbrella group had been discussing a proposal by chairman Ahmed Moaz al-Khatib to hold direct talks with President Bashar al-Assad's regime.
But while saying that while peace negotiations could accommodate "honourable members of the Baath Party and the political apparatus", the group insisted "Assad and the security and military command cannot not part of any political solution."
Khatib had offered to talk to regime officials without "blood on their hands" -- an initiative welcomed by the Arab League and the United States, as well as Iran and Russia, both close to the Damascus regime.
On the violence in the northern city of Aleppo, Syrian Observatory for Human Rights director Rami Abdel Rahman said at least 14 people were killed and dozens wounded.
The Britain-based Observatory said the number of victims was likely to rise further as many people were trapped under the rubble of collapsed buildings in the eastern district of Tariq al-Bab.
Elsewhere, eight civilians were killed in air strikes on Harasta just northeast of Damascus, and warplanes pounded the eastern Damascus district of Qaboon in a bid to push back rebel forces.
In the southern province of Daraa, 10 people were killed by shelling that targeted the Grand Mosque in the town of Harak, the Observatory said.
The watchdog, which collects reports from a wide network of activists and medics on the ground, gave an initial toll of 99 people killed nationwide on Friday.
Despite the ever-rising brutality of the conflict, which has left an estimated 70,000 people killed, demonstrations continue to be held every Friday nationwide.
The Observatory said protesters in the northern city of Raqa were "greeted by bullets fired indiscriminately by the security forces," leaving at least one demonstrator dead and many others in critical condition.
The latest violence came a day after one of the bloodiest days of the conflict, in which 287 people were killed nationwide, including 61 people whom the Observatory reported dead in a suicide bombing in the central Damascus district of Mazraa.
-- Brahimi condemns 'savage' attack --
UN-Arab League peace envoy Brahimi said he "strongly condemns the savage and horrible explosion in Damascus yesterday, which resulted in the killing of around 100 and the injuring of two hundred and fifty civilians.
"Nothing could justify such horrible actions that amount to war crimes under international law," he added in a statement.
Both the regime and its opponents have blamed the attack near the entrance of the ruling Baath party's main offices on "terrorists."
Another 22 people were killed in an apparently coordinated triple bombing targeting security headquarters in the northern Damascus district of Barzeh the same day, including 19 members of the forces, said the Observatory.
Meanwhile, Human Rights Watch (HRW) demanded unfettered access to Syrian prisons after a prominent peace activist died in custody and another was feared dead.
Omar Aziz, 64, died of heart complications after he was transported to a military hospital. Before his November arrest, he had been delivering humanitarian aid to the beleaguered Damascus suburbs.
"A constellation of abuse surrounds each incident of arbitrary detention in Syria, from the government's unwillingness to even acknowledge who is in their custody, to widespread torture and chilling reports of deaths in detention," HRW said.