BEIRUT (Reuters) - More than 30 people have been killed in the most lethal rebel bombardment of the city of Aleppo since Syria's conflict started four years ago, a group monitoring the war said on Tuesday, an attack condemned by a U.N. envoy visiting Damascus.
Staffan de Mistura called the shelling an indiscriminate attack on civilians but said the government should not retaliate by dropping barrel bombs on populated areas in the divided city.
Syrian President Bashar al-Assad told De Mistura the world needed to recognise the threat of terrorism and prevent foreign states from arming insurgents, state media reported following their meeting on Tuesday.
While large civilian death tolls are frequently reported as a result of Syrian army aerial bombardment of rebel-held parts of the northwestern city, lethal shelling of government-controlled areas is more unusual.
Diplomats and analysts tracking developments in Syria expect intensified battles for Aleppo and other parts of western Syria in the coming weeks after insurgent advances in the northwest, central Syria and the south.
The British-based Syrian Observatory for Human Rights said
34 people were killed, including 12 children, and about 190 were wounded in the bombardment by rebels who are seeking control of the city.
State media had said on Monday that at least 23 people were killed. The attack targeted a mosque where children were taking religious lessons as well as other neighbourhoods, it said.
State news agency SANA published a picture of a limp, blood-soaked child in the arms of a man and another of an older woman in clothes stained with blood and being attended to by medics.
The Observatory, which tracks the conflict using sources on the ground, said the insurgents fired more than 300 shells on government-held neighbourhoods in Aleppo.
The army and rebels have been in a long battle for Aleppo, which was Syria's economic and industrial hub before rebels took over parts it in July 2012. De Mistura has previously tried to broker a ceasefire in Aleppo.
Seizing it would be a big victory for the insurgents against stretched government forces, which have been forced back in other parts of Syria. The conflict has killed more than 220,000 people and driven millions from their homes since 2011.
De Mistura's office condemned the shelling, saying he was in Damascus to urge the Syrian government to stop using barrel bombs - cylinders packed with explosives and shrapnel.
"This indiscriminate attack on civilians in the city of Aleppo took place at the very time when Mr. de Mistura was in Damascus raising with the government the issue of the protection of civilians and the urgent need to stop the use of barrel bombs," it said in a statement.
The government should not retaliate against populated areas by using barrel bombs, it added.
"The Syrian government ... is expected like any government to refrain from killing its own civilians," it said.
Assad has said the military does not use barrel bombs.
"Silence towards the crimes that terrorists are committing will encourage them to continue in their terrorism," state television quoted him as telling De Mistura. "The world must realise the danger that terrorism represents to its security and stability."
Insurgents targeting the capital Damascus further south fired at least 10 rocket-propelled grenades on Tuesday which fell in areas near the Russian Embassy, the Observatory said. It gave no details on casualties.