The commander of a U.S.-supported Syrian rebel group said on Friday the northern countryside of Aleppo province was completely encircled by Syrian government forces and its allies and heavy Russian bombardment continued.
Syrian government troops and their allies broke through rebel defenses to reach two Shi'ite villages in northern Aleppo province on Wednesday, choking opposition supply lines from Turkey to Aleppo city.
The assault in northern Aleppo province, backed by hundreds of Russian air strikes there, has also prompted tens of thousands of people to flee toward the Turkish border and helped derail peace talks in Geneva.
Hassan Haj Ali, the head of a prominent Free Syrian Army group called Liwa Suqour al-Jabal that has received U.S. military training in Qatar and Saudi Arabia, said the aerial bombardment continued.
"The Russian cover continues night and day, there were more than 250 air strikes on this area in one day," he told Reuters.
"The regime is now trying to expand the area it has taken control of," he said. "Now the northern countryside (of Aleppo province) is totally encircled, and the humanitarian situation is very difficult."
Hezbollah's Al Manar television said government forces and allied fighters had taken over the town of Ratyan, which lies close to areas they captured on Wednesday.
The Britain-based Syrian Observatory for Human Rights confirmed the "symbolic" capture of Ratyan, but Haj Ali said it had not yet fallen.
"There are very heavy battles in Ratyan, and an attempt by the regime to storm it. But until now they haven't been able to enter," he said.
Haj Ali reiterated calls for countries backing Syrian rebels to send more military aid, including anti-aircraft missiles, but said he held out little hope for the latter.
"We demand daily more support, but the issue of anti-aircraft (weapons) has become a dream ... the dream that will not come true," he said.
U.S.-made TOW missiles, or guided anti-tank missiles, are the most potent weapon in the rebel arsenal and have been supplied to vetted rebel groups as part of a program of military support overseen by the Central Intelligence Agency.
But while they have helped rebels to slow advances on the ground, they are of little use against fighter bombers.