Syria's opposition National Coalition decided on Friday to form a government to run areas of the country "liberated" by rebels and will meet in early March to name a prime minister, a spokesman said.
"We agreed to form a government to run the affairs of the liberated areas," Walid al-Bonni said after a meeting in Cairo.
He added that the coalition would meet on March 2 to decide on the composition of the planned government and to choose its head, with members of the group saying the gathering would take place in Istanbul.
Bonni said he hoped the rebel government would be based in Syria.
The opposition group had been meeting since Thursday to discuss a range of topics, most notably a suggestion by Coalition chief Ahmed Moaz al-Khatib to open negotiations with members of the regime who do not have "blood on their hands."
Also Friday, at least 12 people, including children, were killed and dozens wounded when three surface-to-surface missiles struck in the northern Syrian city of Aleppo district, a watchdog said.
"At least 12 bodies have been recovered so far and there are more than 50 people wounded," Syrian Observatory for Human Rights director Rami Abdel Rahman told AFP by phone.
The Britain-based Observatory said the number of victims was likely to rise, as many people were trapped under the rubble of collapsed buildings in the eastern district of Tariq al-Bab.
In other developments, international peace envoy Lakhdar Brahimi said Friday that a devastating bomb blast in the Syrian capital was a "war crime" that had left about 100 people dead.
The toll given by Brahimi was grimly higher than the 61 dead given by Syrian activists after a suicide bomber staged the attack Thursday near the entrance to President Bashar al-Assad's ruling party offices.
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 fifty civilians.
"Nothing could justify such horrible actions that amount to war crimes under international law," the UN-Arab League envoy added in a statement.
Brahimi called last month for the UN Security Council to set up an independent international investigation for "such crimes" in Syria.
Assad's government and the opposition have blamed the Damascus attack on "terrorists."