The Syrian military has begun a major ground offensive on the country's second city of Aleppo. The advance in northern Syria has been supported by the Russian air force.
The Syrian Observatory for Human Rights said on Friday that in the past 24 hours, "dozens" of Russian airstrikes had struck the area which is controlled by a various groups including rebels, Islamist fighters and al Qaeda's Syria affiliate, al Nusra Front.
"The Syrian army started a new front on Friday and advanced to take control of the villages of Abteen and Kaddar about 15 kilometers (9 miles) south of Aleppo city," said Observatory head Rami Abdel Rahman.
According to a senior military source in Syria, the assaults are also being supported by hundreds of fighters from Iran and Lebanon's Hezbollah.
"This is the promised battle," the source told Reuters news agency.
Concerns over Russia
Several members of the international community have been questioning Russia's intentions since Moscow launched its aerial campaign in late September. Some Western officials have described the move as a ploy to bolster Syrian President Bashar al-Assad's regime.
Russia maintains, however, that they are only targeting areas held by "Islamic State" (IS).
The safety of air personnel has also become and issue with the US and Russia both flying combat missions over Syria.
The offensive on Friday followed a similar advance by Syrian and Russian forces on Thursday on rebel-held areas of the central province of Homs.
The Observatory reported on Friday that at least 60 people, including 30 women and children, had been killed during the strikes. Seventeen rebel fighters were also among the dead.
The Syrian conflict has displaced millions and left more than 250,000 people dead since it erupted in 2011, following a government crackdown on people protesting President Assad's regime.
ksb/kms (Reuters, AFP, dpa)