President Bashar al-Assad named a new prime minister on Thursday to replace Syria's most senior government defector and his forces pounded rebels in a strategic district of Aleppo.
Assad appointed Wael al-Halki, a Sunni Muslim from the southern province of Deraa where the Syrian uprising erupted 17 months ago, to head the government after Riyad Hijab fled on Monday after spending only two months in the job.
Hijab's dramatic escape across the border to Jordan dealt another blow to Assad's authority, already shaken by the assassination last month of four of his top security officials and rebel gains in Damascus, Aleppo and swathes of rural Syria.
But Assad, grimly shrugging off such setbacks, seems locked in a desperate contest with his mostly Sunni opponents seeking to end half a century of Baathist rule and topple a system now dominated by members of the president's minority Alawite sect.
Assad has focused his fierce army counter-offensive on Syria's two main cities, reasserting control over much of Damascus before taking the fight to the northern commercial hub.
Rebels fighting in the Aleppo district of Salaheddine, a southern gateway to the city, said they had been forced to fall back from some frontline positions on Thursday by withering bombardment which had reduced buildings to rubble.
"There have been some withdrawals of Free Syrian Army fighters from Salaheddine," rebel commander Abu Ali said, adding that rebels were regrouping for a counter-attack.
Another combatant said at least 30 people had been killed in Salaheddine, where fighting has ebbed and flowed for two days.
As the battle for Aleppo raged, Assad's closest foreign backer Iran gathered ministers from like-minded states for talks about how to end the conflict. Russia, another ally of Damascus, said its ambassador to Tehran would attend.
Assad cannot afford to lose Aleppo if he is to remain a credible national leader. Already stretched by rebel activity in many parts of the country, the military, despite its advantage in tanks, warplanes and helicopters, has had to cede ground elsewhere as it struggles for control of Syria's biggest city.
As part of a broader army offensive, Assad's forces attacked rebels on several fronts including a neighbourhood near the airport in southeast Aleppo, several eastern districts, and a town on Aleppo's northwestern outskirts, state media said.
Reuters journalists in Tel Rifaat, 35 km (20 miles) north of Aleppo, watched a Syrian air force jet diving and firing rockets, causing villagers to flee in panic.
Explosions rang out and black smoke billowed from an olive grove. A truck was engulfed in flames. Six children and a crying woman fled their tiny home. One woman held the Koran above her head, kissing it, and another banged her head in her hands. Men emerged to stare at the sky and throw their arms up in despair.
Abu Ali, a rebel brigade commander, told Reuters in Aleppo he had rallied 400 fighters of the Amr bin al-Aas brigade in response to Wednesday's army offensive in Salaheddine.
"We are here to be martyred," he told his men before joining them - despite being confined to a wheelchair by a recent war wound - and coordinating their operations via walkie-talkie.
Though sympathetic to the rebels, Western powers, Turkey and Sunni Arab states have not intervened militarily. Russia and China have blocked United Nations action against Assad, while Iran has tried to bolster the Syrian leader in an Arab world where many view non-Arab, Shi'ite Iran as a menace.
Iranian President Mahmoud Ahmadinejad has billed the Tehran meeting of a dozen countries as an opportunity "to replace military clashes with political, indigenous approaches to settle the disputes". Those attending would have "a correct and realistic position" on the Syrian conflict, a senior Iranian diplomat said this week, indicating a one-sided discussion.
"The Islamic Republic's support for Assad's regime is hardly compatible with a genuine attempt at conciliation between the parties," said one Western diplomat based in Tehran. It showed Iran was "running out of ideas", he added.
Syrian rebels, who have accused Iran of sending fighters to help Assad's forces, seized 48 Iranians in Syria on Aug. 4, saying they were members of Iran's Revolutionary Guards.
An Iranian Foreign Ministry official said on Thursday that all the prisoners were alive, contrary to statements by their captors that three had been killed in an air raid.
Iranian Foreign Minister Ali Akbar Salehi has acknowledged that some of the men were retired soldiers or Revolutionary Guards, but said they were religious pilgrims, not combatants.
Damascus and Tehran accuse Turkey, Saudi Arabia, Qatar and Western nations of stoking violence by backing Syrian rebels.
The Syrian Observatory for Human Rights, a British-based opposition watchdog, said more than 60 people had been killed across Syria on Thursday. It put Wednesday's death toll at 170, including 33 civilians in Aleppo.
The violence in Syria has forced tens of thousands of people to flee into neighbouring countries, and about 2,400 refugees, including two generals, arrived in Turkey on Tuesday night.
Near the Syrian border town of al-Dana, a crowd of refugees from Aleppo crammed through a frontier fence as Turkish soldiers tried to keep order. "We could not endure any more," Ahmad Shaaban, a grocer from Salaheddine, told Reuters.
"We have been deprived of everything. They have burnt our homes and have deprived us of our livelihood."