Syrian opposition rebels shelled government-controlled areas in the northern city of Aleppo on Tuesday killing at least four people and wounding 50, a group that monitors the conflict said.
The Syrian Observatory for Human Rights said there was heavy shelling in several neighbourhoods in al-Serryan and al-Zahraa, as well as nearby areas in the western sector of Aleppo city.
"So far we have documented four killed, including a child, and 50 others wounded," Rami Abdel-Rahman, who heads the Britain-based Observatory, told dpa.
The state-run SANA news agency reported six dead and 37 wounded.
The Syrian government excluded Aleppo from a temporary ceasefire that started Saturday in the capital Damascus, nearby Eastern Ghouta and the coastal area of Latakia.
At least 244 civilians have been killed in Aleppo since April 22, according to the Observatory.
Once Syria's commercial hub, Aleppo is now divided between the government-held west and the rebel-controlled east.
The fresh attacks come as UN Syria envoy Staffan de Mistura is scheduled to meet Russian Foreign Minister Sergei Lavrov in Moscow on Tuesday.
The Observatory also said that airstrikes on Monday night and early Tuesday targeted al-Raqqa, the de facto capital of Islamic State in north-eastern Syria, killing 13 civilians and five militants.
Abdel-Rahman of the Observatory said there were 35 strikes, but did not specify whether they were carried out by Russian planes or the US-led coalition.