The Russian Defence Ministry said on Tuesday that Russian and Syrian military planes had not launched any air strikes on Aleppo in the last seven days, contradicting a monitor who says frontline areas in the city have been bombed since Saturday.

Major-General Igor Konashenkov said in a statement that Russian and Syrian planes had not even approached let alone bombed the devastated city since Moscow said it was suspending air strikes last Tuesday ahead of a pause in hostilities.

"Flights over Aleppo by the Russian and Syrian air forces have been completely halted for the last seven days," said Konashenkov.

Six humanitarian corridors in eastern Aleppo, which were opened as part of the pause in hostilities to allow civilians to flee, were still operating, said Konashenkov. He said 48 women and children had left the city late on Monday escorted by Russian military officers.

Aleppo was Syria's most populous city before the war, but is now divided into government- and rebel-held areas. Intense bombardment has reduced the rebel-held east of the city to ruins.

Russia has repeatedly complained that its efforts to help civilians evacuate have been thwarted by militants who it says have opened fire on anyone wanting to leave.

Rebels did not accept the ceasefire, which they say does nothing to alleviate the situation of those who choose to remain in eastern Aleppo, and believe it is part of a government policy to purge cities of political opponents.

The Syrian Observatory for Human Rights says there have been no deaths from air strikes inside residential eastern Aleppo since the ceasefire officially began last Thursday.

But it said air strikes had hit frontline areas of clashes in the city since the lull ended on Saturday, for example in southwest Aleppo city.

Air strikes continued on Tuesday outside the city to its west and north, the observatory said.