Rebels in northern Syria on Wednesday seized most of a military base near Aleppo, their third a major battlefield success in as many days, as Russia said it will host talks with both the regime and opposition.
At least another 145 people were killed across Syria on Wednesday, including 66 civilians, the Syrian Observatory for Human Rights told AFP.
The majority of Base 80 "has come under insurgent control" a day after the rebel fighters launched a coordinated assault on two airports that the strategic facility's troops are tasked with securing, the Observatory said.
Dozens of rebels and forces loyal to President Bashar al-Assad were killed, the Britain-based group which relies on a network sources on the ground for its information told AFP.
The insurgents on Tuesday overran a military air base at Al-Jarrah, also in Aleppo province, after taking control of Syria's largest dam in the neighboring province of Raqa the day before.
Activists have said Aleppo's insurgents shifted their focus from targets in the provincial capital to military bases because they are a source of ammunition and weaponry, and to put out of action warplanes used to bomb rebel bastions.
In Aleppo city itself, meanwhile, electricity and water supplies were down for a fourth day, said the anti-regime Aleppo Media Center, warning of a "humanitarian disaster" in what was once Syria's commercial hub.
Commenting on the rebels' advance in Aleppo province, Observatory director Rami Abdel Rahman told AFP the army may be giving up on parts of northern Syria in order to secure the center.
"The army is barely resisting the rebels' advance on bases in the north. Meanwhile, it is resisting with ferocity the insurgents in Daraya (southwest of Damascus) and Homs (central Syria)," Abdel Rahman said.
"The regime understands it cannot survive a transition without securing some land to bargain with," he added.
Despite the advances, regime warplanes carried out several air raids on rebel areas in Aleppo province while army tanks shelled the east Damascus district of Jobar, the Observatory said.
Insurgents have secured enclaves in the eastern and southern suburbs of Damascus, and the army is trying hard to push them out.
Meanwhile, a top Russian diplomat said Syrian Foreign Minister Walid al-Muallem and Ahmed Moaz al-Khatib, the head of the opposition umbrella National Coalition, would make separate visits to Moscow for talks in the coming weeks.
Speaking after talks with Jordan's foreign minister, U.S. Secretary of State John Kerry hinted the U.S. and Jordan could take renewed steps to urge Russia, a key Syria ally, to bring more pressure on Assad to quit.
"I still remain hopeful that there may be an equation where the Russians and the United States could in fact find more common ground than we have found yet with respect to that," Kerry said, adding that Jordan's King Abdullah II was expected to visit Moscow.
Khatib announced two weeks ago he was willing to hold talks with the Assad regime, subject to conditions including the release of 160,000 detainees. The call was backed by Arab League chief Nabil al-Arabi.
He later urged Assad's regime to respond positively to his call for talks, saying, "The ball is now in the regime's court. They will either say yes or no.”
Khatib has met with Russian Foreign Minister Sergei Lavrov. Moscow, which has supported Assad throughout the civil war in the country, later said it wanted to keep in regular contact with the Syrian opposition.
At the same time, Moscow has indicated it is continuing its export of military hardware to the Assad regime.