Russian warplanes pounded the southern edges of Syria’s Aleppo city overnight, slowing a "last chance" terrorist offensive against Syrian army forces

Russian warplanes pounded the southern edges of Syria's Aleppo city overnight, slowing a "last chance" terrorist offensive against Syrian army forces, activists said Tuesday.

Extremist and terrorist groups launched a major assault Sunday on the southern edges of the divided city in a bid to break a government siege of eastern militant-held neighborhoods.

But army fighters backed by Russia's air force have put up a fierce defense of the southwestern outskirts.

"The Russian raids didn't stop all night on the front lines" there, said Rami Abdel Rahman, head of the Syrian Observatory for Human Rights, a British-based activist group.

"This has slowed the offensive and allowed government troops to retake five of the eight positions that rebels had taken since Sunday," he added.

Abdel Rahman said militants from the Fateh al-Sham Front, formerly Al-Qaeda affiliate Al-Nusra Front, and allied terrorists were struggling to hold positions they had seized.

The Observatory said 50 terrorists and allied extremists had been killed since the operation began on Sunday.

At least 30 civilians have been killed since Sunday in terrorist bombardment of government-held southwestern districts of Aleppo, activists said.

"This battle is the last chance for rebels. If they lose, it will be difficult for them to launch a new assault to break the siege," Abdel Rahman said.