The Syrian army said it had taken a strategic district of Aleppo on Tuesday, in what would be the most important advance in the divided city by Damascus and its allies in weeks, but rebels said the battle was not over.

The 1070 Apartments district is located on the southwestern outskirts of Aleppo and lies alongside the government's corridor into the parts of the city that it controls.

The Syrian Observatory for Human Rights, a UK-based group that reports on the war, said government forces and their allies had seized full control of the district, calling it the most significant gain by the government in Aleppo since September.

A Syrian military source said the army and allied forces were in complete control of the area and surrounding hills. They have made repeated efforts to oust rebels from the 1070 Apartments area since the summer.

A military media unit run by the Damascus-allied Hezbollah carried a similar report. Hezbollah, a Lebanese Shi'ite Muslim group, is fighting in support of Damascus.

But officials in two rebel groups fighting in Aleppo said the battle was still raging. Yasser Alyousef from the political office of the Nour al-Din al-Zinki group said rebels had recovered positions they had lost on Monday.

"There is still a battle and the result has absolutely not been decided," added the second official, Zakaria Malahifji, head of the political office of the Fastaqim rebel group.

Syrian government forces backed by allied militias and Russian air power launched a major assault on rebel-held eastern Aleppo in September, after besieging the area that the United Nations says is home to 275,000 people.

Insurgents launched a counter attack aimed at breaking the siege on Oct. 29, targeting government-held western districts of Aleppo in an offensive that included jihadist groups and insurgents fighting under the Free Syrian Army banner.

But their progress slowed after early gains.

Russia says its air force has been observing a moratorium on air strikes on the rebel-held districts of eastern Aleppo since Oct. 18. The Observatory and emergency workers in eastern Aleppo said heavy air strikes had killed hundreds of people, and hit hospitals and other civilian facilities prior to that.

Insurgent shelling of government-held western Aleppo has meanwhile killed dozens of people, the United Nations said last week in an update on the humanitarian situation in the city.