Syrian forces have been bombing the town of Yabroud near the Lebanese border, backed by a ground offensive according to some reports.
Syrian security sources described it as a routine operation to root out “armed terrorist groups”.
But in Aleppo the accusations of atrocities are directed at the government.
Footage published on the internet, which experts say is credible, is said to show the moments after one of several “barrel bombs” fell on the northern city on Monday.
Smoke fills the air, casualties are carried away on stretchers and there is a general atmosphere of panic.
The opposition says the drums packed with explosives have killed hundreds of people in Aleppo alone in the past week.
Refugees who have fled Syria watch events from a distance, and note that talks in Switzerland have coincided with more not less violence.
“Geneva, Geneva, Geneva, we’ve been waiting for the Geneva conference to find a solution, but it’s brought us nothing,” said Dahi al-Hammadi, who comes from Deir al-Zour in Syria and now lives at the huge Zaatari camp in Jordan.
The influx of refugees into the east Bekaa region of Lebanon has put pressure on that country’s resources and the economy.
Shops in the town of Arsal now face fierce competition from the Syrian arrivals. Mahmoud has sold desserts for 20 years.
“Now I earn much less. I sell a packet of sugar cookies for 6,000 lira. The Syrians have opened many dessert shops here and they sell them for 4,000. Now I have fewer customers and I have to reduce prices so I earn less and less,” he says.
In three years, the number of refugees has trebled the town’s population to 100,000.
The Lebanese understand the Syrians’ plight but say their own livelihoods are under threat.