Syria has sent thousands of troops surging towards the city of Aleppo, where regime forces are trying to reclaim areas held by opposition forces, opposition sources say.
A spokesman for Free Syrian Army said troops had been moved from the northwestern province of Idlib to fight in Aleppo.
"A large number of troops is being redeployed from Jabal al-Zawiyah to Aleppo, which is strategically more important for the regime than Idlib," Colonel Abdel Jabbar al-Oqaidi, the FSA's Military Council spokesman in the city told the AFP news agency on Wednesday.
Syrian army helicopters reportedly fired rockets and machineguns near central Aleppo on Tuesday trying to enlarge their foothold in the city, forcing residents to flee.
Residents said fighter jets were flying over some opposition-held neighborhoods, and that helicopters were firing at eastern and southern parts of the city located around only 3km east of Aleppo's ancient citadel in the city center.
"I heard at least 20 rockets fired, I think from helicopters, and also a lot of machinegun fire," said a resident near one of the areas being shelled, who asked only to be identified by his first name Omar.
"Almost everyone has fled in panic, even my family. I have stayed to try to stop the looters, we hear they often come after an area is shelled," he added.
Reinforcement
Al-Oqaidi said he believed the reinforcements were being sent to Aleppo because of the intensity of clashes in the city, where several districts were "liberated" on Monday.
"There are clashes right now in Aleppo, so fierce that many of their troops are running away, while dozens of others are defecting on the spot," he said. "Their morale is very low."
He had earlier announced "the start of an operation aimed at liberating Aleppo from the blood-stained hands of Assad's gangs," referring to loyalists of President Bashar al-Assad.
A commercial hub and home to 2.5 million people, Aleppo recently became a new front in the country's 16-month uprising, after being largely excluded from the violence.
Elsewhere in the province, residents accused government troops of indiscriminately firing on the town of al-Jinah.
Amateur video obtained by Reuters news agency appeared to show the aftermath of fighting in which residents said three people were killed and another wounded when a car was hit by a mortar shell.
Opposition activists said regime troops and opposition forces have fought fierce battles in the area.
"What is the fault of this village to be hit with these shells? Ten shells on a daily basis and this village does not have any sign of “armed groups”?" a resident said, saying the village had been targeted "only because we called for freedom".
The violence in Aleppo came as Hillary Clinton, the US secretary of state, insisted there was still time for Assad to hand over power, stressing the pace of events in Syria was speeding up.
"We do believe that it is not too late for the Assad regime to commence with planning for a transition to find a way that ends the violence," she told reporters, adding that things were "accelerating inside Syria".
PHOTO CAPTION
Demonstrators protest against Syria's Presient Bashar Al-Assad at Binsh near Idlib July 23, 2012.
Al-Jazeera