At least six people were killed when Syrian regime helicopters dropped explosive-filled barrels on a neighbourhood of the northern city of Aleppo on Saturday, a monitoring group said.
The Syrian Observatory for Human Rights said the toll could rise in the incident, the latest in which government troops have used the controversial weapon.
The raid comes a day after Syria's Defence Minister General Fahd al-Freij visited parts of northern Aleppo province, where the army has made advances in recent weeks.
State news agency SANA said Freij "explained that he was visiting Aleppo to salute the heroic fighters of the Syrian Arab army."
He said he was offering thanks for "their great victories and their liberation of many areas in Aleppo... the most important of which is Aleppo internatinal airport and the surrounding area, which is now able to receive aircraft."
Aleppo airport was closed for around a year because fighting in the surrounding area made it too dangerous for aircraft to land there.
But in November, the army gained ground in the area and the airport was reopened to air traffic on January 22.
Elsewhere in Aleppo city, the Observatory said fighters from the jihadist Islamic State of Iraq and the Levant detonated two car bombs targeting headquarters of rebel forces.
There were no immediate details on casualties in the blasts.
Moderate and Islamist opposition fighters from an array of groups have been battling the jihadist ISIL since early January, after accusing the group of a spate of abuses against civilians and rebels.
Meanwhile, in the central province of Hama, the Observatory said at least 12 members of the government's forces, including pro-regime militiamen, were killed in fighting around the town of Morek.
The group said rebel forces, including the Al-Nusra Front, which is affiliated to Al-Qaeda, had seized the town in fierce fighting overnight, cutting a strategic supply line for the regime that runs from Hama city north to two military bases in neighbouring Idlib province: Wadi Deif and Hamidiyeh.
In southern Damascus, the UN agency for Palestinian refugees UNRWA said it had carried out a third consecutive day of aid distributions in the Yarmuk camp.
The Palestinian refugee camp has been under a choking siege that the Observatory says has left 88 people dead from starvation and lack of medical care.
"So far today, UNRWA workers on the ground in the Yarmouk Palestinian refugee camp in Damascus have distributed 480 food parcels," UNRWA spokesman Chris Gunness said.
He said the agency has distributed 2,624 food packages in the camp since January 18 to some 18,000 Palestinian civilians trapped inside.
"There is a large crowd near the distribution point and the situation is tense. These tense scenes attest to the profound levels of need," he added.