Syrian government forces dropped barrel bombs on rebel-held districts of Aleppo Wednesday, killing 13 people as they pressed an assault southeast of the northern city, a monitoring group said.
More than 20 of the controversial unguided munitions were also dropped on the town of Daraya, southwest of the capital, the Syrian Observatory for Human Rights said.
Government troops meanwhile battled rebel forces near Krak des Chevaliers, a famed Crusader castle between the central city of Homs and the Mediterranean coast, the Britain-based group added.
The fighting came even as both the government of President Bashar al-Assad and the opposition National Coalition reported "positive" results at peace talks in Geneva after four days of deadlock.
A woman and a young girl were among the dead when government helicopters dropped barrel bombs on the Maadi district of south Aleppo, the Observatory said.
The explosives-packed barrels were also dropped on the nearby Salhin, Sheikh Najjar and Ashrafiyeh neighbourhoods, it added, without having any immediate word on any casualties.
The opposition National Coalition said it "condemns in the strongest possible terms the Assad regime's continued abhorrent use of barrel bombs against innocent civilians in residential areas across Syria."
Government forces have launched an offensive to the southeast of Aleppo, Syria's pre-civil war commercial capital, aimed at securing the international highway and expanding their area of control around Nairab airbase, security sources said.
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The offensive has already won them their first gains in the area in more than a year, with the capture of the Karm al-Qasr district on the city's southeastern fringes, the Observatory said Tuesday.
Elsewhere in Aleppo province, clashes erupted between rebels and fighters of the jihadist Islamic State of Iraq and the Levant in the town of Al-Bab.
Despite ostensibly fighting on the same side of Syria's war, clashes between the groups erupted in early January in the face of mounting allegations of horrific abuses by ISIL against both civilians and rival rebels.
At least 1,565 people have been killed in the clashes -- 208 civilians, 878 mainstream rebels and allied Islamists and 459 ISIL fighters, the Observatory said on Wednesday.
Farther south, near Krak des Chevaliers, government forces launched four air raids on the town of Zara, in an area where fierce battles with rebels left 26 people dead on Tuesday, the Observatory said.
As international pressure mounted at the peace talks in Geneva for the two sides to reach agreement on steps to address the plight of civilians trapped by the fighting, a senior official said the government was ready to grant safe passage to all those who wanted to leave the besieged Old City of Homs.
Provincial governor Talal Barazi told the state SANA news agency that "preparations to guarantee the exit of civilians who want to leave the Old City" were complete.
The Old City has been under siege for some 600 days, according to the opposition, with aid agencies unable to enter for more than a year.
There has been disappointment over the failure of the two sides to agree any humanitarian measures, especially for besieged residents of Homs, Syria's third largest city, where UN trucks are waiting for access to deliver food and medical aid.
The regime has agreed to allow women and children to leave besieged areas of the city, but the opposition wants aid to be allowed in.