Clashes between government troops and rebels raged Thursday in opposition bastions of besieged Aleppo as President Bashar Assad's key state backer Iran hosted a gathering of countries for talks on how to end the conflict.
Tehran billed the conference as an attempt to start an alternative political process, separate from Western-led initiatives, to encourage all sides to negotiate.
Speaking at the opening of the conference in Tehran, Iranian Foreign Minister Ali Akbar Salehi said his country rejects any foreign and military intervention in Syria and accused rebels of using civilians as "human shields."
Syrian rebels last week intercepted a bus carrying 48 Iranians in a Damascus suburb and seized them. Rebels claimed the men are military personnel, including some members of Iran's powerful Revolutionary Guard, who were on a "reconnaissance mission" to help Assad's crackdown.
Iran, however, says the 48 were pilgrims visiting a Shiite shrine in Damascus. Salehi said Wednesday that some of the pilgrims are retired members of the army and Revolutionary Guard.
The overwhelmingly Sunni Muslim rebels have also seized 11 Lebanese Shiite pilgrims who have been held in northern Syria since May.
Assad, meanwhile, appointed a new prime minister to replace the one who defected to neighboring Jordan this week. State-run news agency SANA said he appointed Health Minister Wael Nader al-Halqi, a Sunni member of the ruling Baath party from the southern city of Daraa, the birthplace of the 17-month-old uprising.
Al-Halqi replaces Riad Hijab, whose defection was a humiliating blow to the regime. Like nearly all prominent defectors so far, Hijab is a member of Syria's majority Sunnis — the Muslim sect which forms the bedrock of the uprising.
Still, power remains closely held within Assad's inner circle and the most significant leadership is dominated by members of the president's minority Alawite sect, an offshoot of Shiite Islam.
The regime has been trying to drive rebels out of Aleppo for two weeks. But the blistering attacks on rebel positions from the ground and the air appear to be only slowly chipping away at the opposition's grip on its strongholds.
The state news agency claimed Wednesday that Assad's force had regained control of the Salaheddine neighborhood, the main rebel area in Aleppo. But activists said rebels were still putting up a fight there on Thursday.
"It's difficult to know exactly what's going on because of the scale of the bombing, but the rebels are still fighting," Aleppo-based activist Mohammad Saeed told The Associated Press by Skype.
He said troops were using warplanes and tanks to shell the towns of Hreitan and Tel Rifat, some 25 miles north of Aleppo, from where most of the rebels converged on the city.
"They are trying to cut the main lines from Tel Rifat to Aleppo," he said.
Syrian fighter jets launched airstrikes Wednesday on Tel Rifat, hitting a home and a high school and killing six people from one family, residents said.
They said government forces often shelled the village, but that this had been the first airstrike. They acknowledged that there were some rebels in the village, though an Associated Press reporter saw no armed men during a brief drive through the area.
Aleppo holds great symbolic and strategic importance. Some 25 miles from the Turkish border, it has been a pillar of regime support during the uprising. An opposition victory there would allow easier access for weapons and fighters from Turkey, where many rebels are based.
State television in Iran, Syria's closest ally in the Middle East, said Tehran was hosting the conference of "friends" of Syria in the hope of finding a peaceful solution to the crisis.
Salehi said some 30 countries attended the meeting, including Russia and China, as well as Pakistan, Iraq, Algeria and Venezuela.
The meeting was called at short notice and most countries were represented at the ambassador level.
Russia in the past has urged the West to allow Tehran to take part in international discussions on how to settle the Syrian crisis, arguing that the Islamic republic could play an important role. Moscow has been the main protector and ally of Assad's regime, shielding it from the United Nations sanctions over its brutal crackdown on an uprising that has evolved into a full-blown civil war.