Russia said on Tuesday, October 25 it would extend a moratorium on air strikes on Syria's Aleppo into a ninth day, but a monitor and a civil defence official said that rebel-held parts of the divided city had been struck in recent days, Reuters reports.

Defence ministry spokesman Major-General Igor Konashenkov said Russian and Syrian planes had not even approached, let alone bombed, the devastated city since last Tuesday when Russia suspended air strikes ahead of a pause in hostilities.

That moratorium on air strikes was being extended, Sergei Rudskoi, a defence ministry official, said separately on Tuesday, without specifying for how long.

Rudskoi said that meant planes from Syria and Russia, which has been Damascus's most powerful ally in its six-year-old civil war, would continue to stay out of a 10-km zone around Aleppo.

But the Syrian Observatory for Human Rights said air strikes had resumed since the lull in fighting ended on Saturday, focusing on major front lines, including in the city's southwest. There had been no civilian deaths from air strikes inside eastern Aleppo, however, the monitor said.

Ibrahim Abu al-Laith, a civil defence official in eastern Aleppo, also said air strikes and shelling had hit the rebel-held half of the city near front lines in the past week.

"There was artillery shelling ... and there were planes, the city was hit by several strikes," he said, according to Reuters.

The U.S. State Department urged Russia to use the newly announced pause in bombing to ensure the delivery of aid to besieged civilians.

"We obviously welcome any reduction in the violence, but it has to be met with a commitment and an actual delivery of humanitarian assistance, which was the purpose in the first place," State Department spokesman John Kirby told a briefing.

He said Washington would prefer putting in place a longer-term cease-fire to ensure delivery of aid, rather than sporadic pauses like those announced by Russia and Syria in recent days. Multilateral talks in Geneva were attempting to reach that goal, but were having limited success, Kirby said.

"I don't want to couch this as nothing but failure. There has been some progress made, but there's obviously still more work to be done," he told reporters.

German Foreign Minister Frank-Walter urged a renewal of the ceasefire in separate telephone calls with U.S. Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov on Tuesday, according to ministry officials.

He expressed disappointment that it had not been possible to evacuate wounded people from Aleppo and bring in humanitarian relief supplies during the pause in the fighting.

On Tuesday, districts outside the city to the west were hit by air strikes, the Observatory said. Air strikes had continued outside Aleppo during the ceasefire.