Over 20,000 Syrian troops amassed in the Aleppo region on Sunday as part of Syrian President Bashar Assad’s latest attempt to recapture rebel strongholds in Syria’s largest city, the BBC cited military sources saying.

Rebel forces were reportedly close to capturing Aleppo’s ancient citadel and controlled the city’s eastern and southern districts. They prepared themselves for the “strong offensive” to come.

A Free Syrian Army commander reported that Aleppo’s Salah A-Din district was “under the heaviest bombardment since the battle began” two weeks ago, but the government forces have “not managed to advance.”

A senior government official told AFP on Saturday that the “battle for Aleppo has not yet begun, and what is happening now is just the appetizer… the main course will come later.” President Bashar Assad’s forces were “cleansing the terrorist filth” in the latest offensive, Syrian state television said.

An anonymous Syrian army brigadier general was quoted by Sky News saying that government forces had recaptured the Damascus neighborhood of Tadamun, giving the Syrian army full control of the capital.

Assad’s forces have intensified their assault on rebel strongholds since Kofi Annan’s resignation as the UN’s special envoy to Syria on Thursday. Annan unsuccessfullyworked for several months to bring an end to the violence in Syria.

The Local Coordination Committees of Syria reported 67 Syrians killed on Sunday, including 33 in Damascus and eight in Aleppo. Two women and three children were among those killed.

The UK-based Syrian Observatory for Human Rights places the number of killed in the Syrian civil war at over 21,000, including more than 4,200 in July alone, the bloodiest month of fighting to date.