The reported push into Khaldiyeh neighborhood on Thursday came a day after insurgents captured the eastern neighborhood of Rashideen from troops and pro-government gunmen.
Aleppo-based activists Ahmad al-Ahmad and Bahaa Halaby said several factions entered Khaldiyeh, which has a large Kurdish community.
State TV denied the claims and aired a report from Khaldiyeh. It had earlier denied the capture of Rashideen without providing any proof.
State TV and the activists said Rashideen was relatively quiet Wednesday afternoon after heavy fighting overnight.
Aleppo, the country’s largest city and former commercial capital, has seen heavy fighting since rebels seized part of the city in 2012.