Syrian state television Monday announced that a battle to "liberate" Aleppo was about to begin, as activists reported rebel gains in the northern province, dpa reported.
Television showed a line of tanks allegedly heading to "the battle to liberate Aleppo," as speculation rose that the regime would seek to win back northern areas after capturing the central town of al-Kussair last week.
The northern city, Syria's biggest commercial centre before the conflict, has been split into rebel- and government-held areas since July.
The Britain-based Syrian Observatory for Human Rights, a pro-opposition group, said the rebels had managed to take control of the radar tower inside the strategic military airport of Minnigh, the scene of fighting since last August.
State-media played down the report but said jets had raided the outskirts of the airport, some 30 kilometres north of Aleppo, and had killed a number of "terrorists".
Observers were cautious about the prospect of a major government offensive on Aleppo, which lies some 200 kilometres from al-Kussair. Rebels have a strong presence in much of the territory in between.
Rami Abdel-Rahman of the Observatory said the regime was massing troops around Aleppo, but he did not see anything "spectacular or alarming from their reinforcements yet."
"The regime got a boost out of the battle of al-Kussair," a former Syrian general who currently lives in Lebanon told dpa.
"They know the Aleppo battle will not be an easy battle like al-Kussair. The rebels control swathes of land, their rear is covered by Turkey and their supply routes are open," said the general, who asked not to be named.
"I think the talk of an Aleppo battle is partly a military media campaign which the regime is using to play with the nerves of the rebels," he added.
Meanwhile, the Democratic Union Party (PYD), which controls most of Syria's Kurdish areas, issued an international appeal over the situation in a Kurdish city near Aleppo.
"For more than 10 days armed groups along with Salafist elements have surrounded the city of Efrin, effectively stopping the flow of goods, including medicine, baby milk, flour, vegetable oil and fuel, to the city," the PYD said.
Clashes between Kurdish forces and rebels have been taking place around Efrin since May 25, with the two sides trading blame over the start of hostilities.
Some 29 wounded people from al-Kussair arrived in Lebanon and were handed over to the Red Cross, Lebanese activist Ahmed Hojairi told dpa.
More than 200 people from al-Kussair have arrived in Lebanon for treatment since Saturday, most of them rebel fighters.
"Our trip took five days to get Arsaal. Some of the wounded who were with us died on the road, due to the lack of food and medical supplies," said Ahmad, a Syrian doctor who was accompanying the new batch of the wounded into Lebanon.