At least nine civilians have been killed and dozens more wounded after mortar rounds and rockets were fired on a mainly Kurdish residential quarter in the northern city of Aleppo, according to the Syrian Kurdish YPG group.
State-run news agency SANA said Sunday's attack, which wounded at least 40 people, occurred in Sheikh Maqsoud, which has been subjected to shelling for days.
The Syrian Observatory for Human Rights, a UK-based group monitoring the war, said more than 70 rockets and mortar shells were fired by armed groups, including al-Nusra Front.
At least 135 people have been killed since a US and Russia-backed Syria ceasefire started a week ago.
Al-Nusra Front and the Islamic State of Iraq and the Levant (ISIL) group are excluded from the truce.
The ceasefire has brought a sharp drop in violence to much of Syria despite sporadic violations and mutual accusations of breaches.
Global foreign ministers - having cautiously praised "real progress" of the ceasefire - have said the focus is on convincing all parties to return to planned UN-brokered peace talks in Switzerland.
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"We want a speedy resumption of the negotiations in Geneva, but two conditions must be fulfilled: access for all Syrians to humanitarian aid, and full respect of the ceasefire," Jean-Marc Ayrault, French foreign minister, said at a meeting in Paris last Friday held to discuss the truce.
Rapid advances by the Syrian army and its allies in the Aleppo countryside early last month allowed them to cut vital supplies lines by rebels into Aleppo city from Turkey.
The YPG also made advances in that area in the wake of the progress by the government forces.
Source: Al Jazeera and agencies