Syrian regime forces and allied militias have re-imposed their siege on opposition-held parts of the northern city of Aleppo, according to local opposition sources.
Backed by Russian warplanes, regime forces captured several positions near southern Aleppo's Ramousa area on Sunday, cutting opposition supply lines into the city, opposition sources said, requesting anonymity due to fears for their safety.
"The city is now under siege again," one of the sources told Anadolu Agency.
Last month, opposition forces managed to break a crippling regime blockade on several districts of Aleppo.
According to the same sources, clashes remain ongoing in the city as opposition fighters try to push regime troops back from their positions.
In a related development, three civilians were killed Sunday when regime helicopters dropped a number of barrel bombs on opposition-held parts of the city, according to local civil defense sources.
"Three civilians were killed and another 20 were injured in Sunday's attacks," the sources, who insisted on anonymity due to security concerns, said.
Barrel bombs are improvised explosive devices packed with shrapnel and explosive material. Usually dropped from army helicopters, the low-cost munitions are believed to have killed thousands of people since the Syria conflict began more than five years ago.
Syria has been locked in a vicious civil war since early 2011, when the Assad regime cracked down on pro-democracy protests -- which erupted as part of that year's "Arab Spring" uprisings -- with unexpected ferocity and disproportionate force.
Since then, more than a quarter of a million people have been killed and more than 10 million displaced across the war-battered country, according to the UN.
