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.
An estimated 300,000 civilians live in rebel-held neighborhoods of Syria's second city, the U.N. says, and there are fears that they could face starvation.
The rebels have failed to thwart a major Russian-backed army offensive around Aleppo, which has been devastated by Syria'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 neighborhoods are now completely besieged," he told AFP.
The Observatory also reported that five civilians were killed Sunday in regime air strikes on the rebel-held neighborhood of al-Maysar while 16 rebel fighters died in the regime advance on Aleppo.