Beirut: Jihadists and rebels captured strategic military positions on the edges of Syria`s second city Aleppo on Saturday, turning the tables on Russian-backed regime forces besieging the city.
To the northeast, a Western-backed alliance of Arab and Kurdish fighters scored a major victory against the Islamic State group in the town of Manbij after a fierce two-month battle.
The developments have rocked the key northern province of Aleppo, a microcosm of Syria`s chaotic multi-front war that has killed more than 280,000 people.
Rebel and regime forces have fought for control of the provincial capital of the same name since mid-2012, transforming the former economic powerhouse into a divided, bombed-out city.
On Saturday, opposition fighters and allied jihadists captured territory south of Aleppo in a bid to cut off regime forces and open up a new route into besieged rebel-held districts.
"The Army of Conquest... took control of the armament school, where there is a large amount of ammunition, and a large part of the artillery school" at a military academy, said the Syrian Observatory for Human Rights.
The coalition of rebels, Islamists, and jihadists "is about to cut off, by gunfire, the supply route into government-controlled districts", said Observatory head Rami Abdel Rahman.
That road passes through a southwestern suburb of Ramussa and is the last route into Aleppo used by regime troops.
The monitor said more than 500 rebels and government fighters had been killed in the offensive since it was launched on Sunday, as well as 130 civilians.
They included at least seven civilians killed on Saturday in rebel shelling of the regime-held neighbourhood of Hamdaniyeh, according to both the Observatory and Syrian state news agency SANA. Opposition forces -- encircled by the government since July 17 -- are hoping to expand their control in the area and use that route themselves.
"Days ago, I was only thinking about how to get a bite to eat," said Ahmad Adna, a 46-year-old resident of eastern Aleppo.
"Now I`m more optimistic after the Army of Conquest`s advance. I hope today will be the last day of the siege."
The former Al-Nusra Front -- renamed the Fateh al-Sham Front after breaking from Al-Qaeda -- on Saturday announced having captured the two military schools and a third military position.
Drone footage posted by the group online showed a series of explosions in some of those buildings, followed by massive columns of billowing black smoke.
Pictures obtained by AFP show a crumpled body, reportedly of a regime fighter, lying next to artillery pieces lined up in a building newly captured by jihadists.
Abdel Rahman said the advance had left the regime forces "in a very difficult position despite Russian air support".
"This is an existential battle. Whoever wins it will win Aleppo," he said.
State media said the army had sent reinforcements in a counter-offensive to take on "thousands of terrorist fighters".
An army officer told state television troops had advanced in the areas seized by rebels and were inflicting "heavy losses" on them.
"Of course I have faith in the army, but I can`t help being scared. Food is already getting more expensive and the coming days risk being very difficult," said a 34-year-old resident of a government-held western quarter of Aleppo.
"We are thinking about how to leave," he told AFP.Also on Saturday, the US-backed Syrian Democratic Forces alliance handed a major defeat to IS in Manbij.
The Britain-based Observatory said the SDF "took control of Manbij... and are combing the city in search of the last remaining jihadists".
Manbij had been a key transit point along IS`s supply route from the Turkish border to Raqa, the de facto capital of its self-styled "caliphate".
The SDF launched its offensive on May 31 with support from the US-led air coalition bombing IS in Syria since September 2014.
It encircled the town in early June and into it later that month, but its assault was slowed by a jihadist fightback using suicide attackers and car bombs.
The Manbij Military Council -- a key component of the SDF -- said fighting was still ongoing.
"The battles are continuing near the centre of the town. We are in control of 90 percent of Manbij," spokesman Sherfan Darwish said.
Syria`s conflict first erupted in March 2011 with anti-government protests but has since evolved into a fully-fledged war largely dominated by jihadist groups.
In addition to more than 280,000 dead, the war has forced half the population to flee their homes.