Syrian activists say government forces, backed by Russian air strikes, have advanced in Aleppo, pressing their weeklong offensive to take the rebel-held part of the northern city.
The Britain-based Syrian Observatory for Human Rights said on October 2 that the regime troops and allied paramilitaries made territorial gains in the northern part of Aleppo.
It added that there was fierce fighting all along the front line that cuts the city in two.
"The Russians have been instrumental in this advance with their intense air raids in support of the regime forces in Aleppo," said the observatory's head, Rami Abdel Rahman.
Meanwhile, the UN's undersecretary-general for humanitarian affairs, Stephen O'Brien, said he was "deeply alarmed by the ferocious pummeling of eastern Aleppo," where 275,000 people are besieged.
"The health system is on the verge of total collapse with patients being turned away and no medicines available to treat even the most common ailments," O'Brien said in a statement.
On October 1, a medical charity said Russian and Syrian air raids in eastern Aleppo forced the closure of the largest hospital in the area and killed two people.