By Ray Sanchez and Merieme Arif
(CNN) — At least 21 people have been killed since Friday in tit-for-tat clashes between Syrian regime forces and rebels in the besieged city of Aleppo, the UK-based monitoring group Syrian Observatory for Human Rights (SOHR) reported.
The rights group said army forces, backed by Hezbollah militants and seeking to put down a new rebel offensive, on Saturday retook pockets of neighborhoods where rebel fighters a day earlier unleashed a series of deadly car bombings and mortar assaults.
The rebel offensive was repelled in part by renewed Russian and Syrian airstrikes targeting parts of west, south and southwest Aleppo, SOHR reported.
Opposition social media on Friday showed video of rebel tanks, armored personnel carriers, Grad rockets and artillery firing from the southwest of the city.
On Saturday, airstrikes and shelling in the Salaheddine neighborhood killed at least three people and wounded five others, according to SOHR. Rebels countered with intense shelling that wounded more than 12 people in regime-held positions in western parts of the city.
The city has long been divided between the government-controlled western section and the rebel-held pockets to the east.
There were conflicting reports on the number of casualties.
At least 21 people have been killed since Friday, including a woman and two children, as a result of rebel attacks, SOHR reported. SANA, the Syrian state news agency, reported at least 13 deaths as of Saturday.
At least six people were injured, including a child, when rebel shells rained down on the al-Hamadania and Salah-Eddin neighborhoods in Aleppo, a source at Aleppo Police Command said on Saturday.
SOHR reported intense fighting Saturday in western parts of the city.
Russia’s military had asked President Vladimir Putin for permission to resume airstrikes on the eastern part of Aleppo after a lull in fighting last week. But Putin said the resumption of airstrikes “would be inexpedient,” according to Kremlin spokesman Dmitry Peskov, who was quoted by the Russian state news agency Tass.
The rebel attacks come after Syrian government and allied Russian forces declared a unilateral ceasefire last week, which brought several days of relative calm following weeks of intense aerial bombardment.
But the ceasefire effectively ended Sunday when warplanes resumed bombing the city, according to residents.
The United Nations blames both sides in the conflict for failing to take advantage of the ceasefire to allow the evacuation of some of the hundreds of thousands of civilians believed to be trapped in eastern Aleppo.
The UN Under-Secretary-General for Humanitarian Affairs said on Wednesday that at least 400 people had been killed by Russian and Syrian government aerial bombardment of eastern Aleppo in less than a month.
Stephen O’Brien also told the UN Security Council that so far in October rebel mortar strikes have killed at least 100 people, including 17 women and 22 children.
Since the war began in 2011, an estimated 400,000 Syrians have been killed, according to the United Nations.
In the five years since the beginning of the civil war, over four million people have been forced to flee their homeland, according to estimates from the United Nations. Around 8.7 million more have been displaced internally and a ceasefire is the only hope for many who want to see an end to the ongoing violence.
There are four main factions of fighting groups throughout the country: Kurdish forces, ISIS, other opposition (such as Jaish al Fateh, an alliance between the Nusra Front and Ahrar-al-Sham) and the regime of President Bashar al-Assad.
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