Syrian government forces have captured a central rebel-held area in Aleppo after a week of air strikes, as a military official vowed that the offensive would continue until the insurgents are "wiped out."
Syrian state TV said troops captured Farafra, near Aleppo's famous citadel, and that fighting is under way near the historic core of the northern city.
Aleppo, Syria's largest city and former commercial centre, has been fiercely contested since rebels captured several eastern regions in 2012.
Those areas are now under siege, and over the past week have endured the worst aerial onslaught since the start of the war, with more than 200 people killed and several buildings flattened.
The battle for the city still appears deadlocked. Government forces captured the Handarat area on the northern edge of Aleppo over the weekend, only to lose it hours later.
The contested historic quarter of Aleppo, one of the world's oldest cities, is home to the Umayyad Mosque, a Unesco world heritage site. The 11th-century minaret of the famed mosque collapsed in April 2013 during fighting.
The UK-based Syrian Observatory for Human Rights, which relies on a network of activists inside Syria, confirmed government forces are advancing on the old quarter.
"There was intense shelling earlier. It seemed the (government) was preparing for the attack," said Ibrahim Alhaj, a member of the Syrian Civil Defence, volunteer first responders also known as the White Helmets.
He added that news from the front line suggests a large mobilisation of pro-government militias in the old city.
Mr Alhaj and activist Yassin Abu Raed, who is based outside the city, said rebels were able to repel the offensive.
Mr Abu Raed said five troops were killed in the fighting. Alhaj said the house of his parents was shelled earlier, but that he was able to rescue them and bring them to his own home.
The latest escalation came after a week-long ceasefire brokered by the US and Russia unravelled, which each side accusing the other of violating the agreement.
A Syrian military official in the capital, Damascus, said operations in Aleppo will continue until the "terrorists" in the eastern parts of the city are "wiped out".