Syrian rebels guard a checkpoint in the northern city of Aleppo. (Bulent Kilic, AFP/Getty…)
BEIRUT — Fierce fighting was reported in the northern Syrian city of Aleppo on Tuesday as rebels said their forces were pushing toward the center of the nation's business and financial hub.
In Washington, Secretary of State Hillary Rodham Clinton predicted that opposition gains would result in a rebel "safe haven" being secured in Syria.
And there were unconfirmed reports in Arab-language news media that Syria's ambassador to Cyprus had defected, becoming the latest official to abandon President Bashar Assad's regime.
As the embattled government has regained control of the capital, Damascus — where battles raged for almost a week — the focus of fighting in Syria has shifted to Aleppo, home to more than 2 million people.
For months, Syria's two principal cities had been relatively insulated from fighting in strife-ridden provinces. In the last 10 days, however, rebel forces have mounted concerted attacks in both cities.
Rebel gains have been especially sweeping in northern Syria, close to Turkey'ssouthern Hatay province, a logistics center for the Syrian opposition. Insurgents may be intent on securing a "liberated" zone in the north, a strategy similar to what happened last year in Libya, where rebels seized much of the east, including its largest city, Benghazi.
"We have to work closely with the opposition," Clinton said, "because more and more territory is being taken, and it will eventually result in a safe haven inside Syria, which will then provide a base for further actions. The opposition has to be prepared. They have to start working on interim government entities."
There were reports Tuesday evening that government forces in Aleppo had used warplanes to fire rockets at rebel positions in several neighborhoods. The use of fixed-wing aircraft, if confirmed, would represent a significant escalation in the government's efforts to put down the more than 16-month rebellion against Assad.
Although security forces have often employed helicopter gunships, there has been no confirmed use to date of the military's substantial fleet of fixed-wing aircraft, capable of punishing bombing and strafing runs.
Opposition activists said that rebels were nearing Aleppo's historic old city and that the government was counterattacking with artillery, helicopters and warplanes. There were reports of dozens of injured people in field hospitals, including civilians caught up in the clashes.
"It has begun to get close to the center of Aleppo," Hashem Abu Muhammed, an Aleppo opposition activist who is currently outside the country, said via Skype.
The opposition also said authorities had crushed a revolt at a prison in Aleppo, leaving more than a dozen people dead.
It was impossible to confirm the extent of the fighting amid conflicting and fragmentary reports from the two sides.
The official Syrian state news service said authorities in Aleppo had inflicted "heavy losses" on "terrorists," the official label for the armed opposition. Many rebels surrendered, the news agency said.
Aleppo, more than 200 miles north of Damascus, sits relatively close to the Turkish border, an area where rebels have gained control of wide swaths of territory and several border crossings. Rebel strategists say supply lines into Aleppo are more reliable than those into heavily defended Damascus.
Rebel commanders say their intent is to seize Aleppo and consolidate control of much of northern Syrian. But whether taking the city was a realistic goal remained a question mark. The armed opposition has sent out a call for all rebel brigades in the region to converge on the city.
The government has fought tenaciously to ensure that the opposition does not exert long-term control over any territory. Defections, however, have cut into military ranks at a time when troops are forced to fight on many fronts.
Government forces enjoy a tremendous advantage in firepower, including armored vehicles, tanks, artillery and aircraft. That edge has allowed the military to oust rebels from other contested zones, including the central cities of Homs and Hama.
On some occasions, government forces have withdrawn from rebel-held districts and resorted to pounding insurgents with artillery and tank shells. Whether a similar scenario is unfolding in Aleppo was unclear.
A Times staff writer in Los Angeles contributed to this report.