Syrian regime forces besiege rebel-held areas of Aleppo
Opposition-controlled parts of Syria's battered northern city Aleppo came under total siege on Sunday, after government forces severed the last route out of the east.
Beleaguered rebels have failed to thwart a major Russian-backed army offensive around Aleppo, which has been devastated by the country's five-year conflict.
On Sunday, regime fighters descended on the Castello Road and fully cut it, said Rami Abdel Rahman, head of the Britain-based Syrian Observatory for Human Rights.
"The eastern neighbourhoods are now completely besieged," he told AFP.
The Observatory said at least 16 rebel fighters were killed Sunday in the regime advance on Aleppo, which is divided roughly between government control in the west and rebel control in the east.
The Castello Road had been used by rebels but also by shopkeepers bringing in produce for residents and by villagers visiting relatives in the city.
"Aleppo is now 100-percent besieged," a rebel fighter from the Aleppo Revolutionaries group told AFP.
"The army has reached the road and even arrested a group of civilians who were walking there," the fighter said.
"They are now setting up sandbag barriers," he added.
Facebook pages run by Aleppo-based activists urged civilians to stay away from the route to avoid being arrested or wounded.
Sieges by both the regime and its opponents have had a devastating impact on other areas of Syria, including the town of Madaya where aid groups say dozens of people have died from starvation and malnutrition.
According to the United Nations, nearly 600,000 people are living under siege in Syria, most of them surrounded by government forces.
Eastern Aleppo is not yet designated by the UN as besieged, but residents have already complained of food shortages and skyrocketing prices.
Shopkeepers have begun rationing their products and there have been long queues outside bakeries.
A leading opposition group had warned last week that hundreds of thousands of civilians in Aleppo were at risk if the Castello Road was cut.
Anas al-Abdeh, head of the Istanbul-based opposition National Coalition, said his group feared "that if the Castello route is totally cut off, more than 300,000 civilians will starve".
Fighters loyal to President Bashar al-Assad sought to seize the Castello Road for nearly two years as part of their campaign to retake the whole of Aleppo.
Armed forces pressed their campaign last week despite announcing several extensions to a fighting freeze marking Eid al-Fitr, the end of the Islamic holy month of Ramadan.
Syria's state media made no mention of the developments on Sunday, but pro-government websites like Al Masdar News reported the advance.
AFP's correspondent in one rebel-controlled neighbourhood said at least six air strikes targeted the eastern opposition neighbourhoods after the route was severed.
On Saturday, at least 28 civilians including children were killed in bombardment of the eastern districts, according to the Observatory, which relies on a wide network of sources on the ground.
Another four people died in rebel rocket fire on the western government-controlled neighbourhoods, it said.
Aleppo was once Syria's commercial powerhouse but has been ravaged by fighting since mid-2012, with several temporary truces failing to bring an end to the violence there.
On Friday, US Secretary of State John Kerry and his Russian counterpart Sergei Lavrov said they had agreed on "concrete steps" to salvage the failing nationwide ceasefire but would not give details.
Russia has demanded that non-jihadist rebel groups -- particularly those in and around Aleppo -- disassociate themselves from Al-Qaeda affiliate Al-Nusra Front in order to avoid being targeted in air raids.
More than 280,000 people have been killed and millions have been forced to flee their homes since Syria's conflict first erupted in March 2011.
UN Syria envoy Staffan de Mistura has urged Russia and the United States to push for a resumption of peace talks next month.
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