Syrian government aircraft have bombed besieged rebel-held eastern districts of the city of Aleppo for the first time in three weeks, said a report citing activists.

The Syrian Observatory for Human Rights reported that at least five people were killed as a number of areas were hit, reported BBC.

The government and its ally Russia halted air strikes in mid-October to allow civilians and rebels to leave.

On Tuesday, activists said the three-week moratorium on air strikes declared by Russia had seemingly ended.

Warplanes and helicopters reportedly bombed the Haidaria, Masakin Hanano, Sakhour, Sheikh Faris, Bab al-Nairab, Qadi Askar and Qaterji districts.

Russia however denied it had resumed attacks on Aleppo, but said it had launched missiles at jihadist groups elsewhere, said the report.

Russia's only aircraft carrier, the Admiral Kuznetsov, was also used in combat for the first time, with Su-33 fighters flying sorties from the eastern Mediterranean.

The UN says weeks of air strikes and shelling have killed more than 700 civilians in the east, while rocket-fire has left scores dead in the government-controlled west.