Syrian rebels and pro-government forces have clashed on several fronts around Aleppo as the country's military command called on militants to lay down their weapons and leave the contested city.
A day after pro-government forces captured the strategic al-Shuqeef hill north of the city, the Britain-based Syrian Observatory for Human Rights monitoring group reported fierce fighting near the hill and in the Bustan al-Basha neighbourhood on Sunday.
There were also clashes in Aleppo's southern Sheikh Saeed neighbourhood.
The government's attempt to penetrate Aleppo's opposition-held eastern side has been accompanied by a relentless campaign of air strikes by Russian and Syrian warplanes.
President Bashar Assad's forces are depending on the Russia bombardment and Iran-backed militias for support.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
A spokesman for the Nour el-Din el-Zinki rebel faction told the Associated Press that foreign fighters were taking part in the government's ground campaign.
He said rebels could identify Lebanese and Iraqi militias by their flags.
An air strike, meanwhile, targeted a rebel headquarters near the central city of Hama, killing at least six militants, the Observatory said.
It was a setback for the rebel campaign to advance on the government-controlled city.
The UN's humanitarian chief, Stephen O'Brien, reported that eastern Aleppo's health system has been "all but obliterated" by shelling and bombardment.
"Medical facilities are being hit one by one," O'Brien said in a statement that called for a 48-hour humanitarian pause to the fighting each week.
The UN estimates 275,000 people are trapped by the government siege.
One of Aleppo's largest hospitals, in the eastern Sakhour neighbourhood, was knocked out of service on Saturday by the air strikes, doctors and activists reported.
The Syrian military command said on state media that government forces would guarantee gunmen safe passage out of opposition-held neighbourhoods.
Russia announced a month ago the Syrian government would give safe passage to civilians wanting to leave eastern Aleppo. Few have accepted the offer.
The UN says at least 320 civilians have been killed since the government announced its offensive on September 22.
The European Union offered to help evacuate Aleppo's hospitals and deliver food, water and medical aid to besieged eastern districts.
EU foreign policy chief Frederica Mogherini has urged international players to unite to make the aid effort work "for the sake of humanity and the political future of Syria".
