ALEPPO, Syria: Syrian government forces on Sunday besieged rebel-held parts of the northern city of Aleppo after severing the last supply route into eastern areas, sparking concern for tens of thousands of civilians. The United Nations says an estimated 300,00 people live in the rebel-controlled neighborhoods of Syria’s second city, and fears are mounting that they could face starvation. After weeks of fierce fighting, government forces seized the strategic Castello Road, said Rami Abdel Rahman, head of the Britain-based Syrian Observatory for Human Rights. “The eastern neighborhoods are now completely besieged,” he said. The UN’s aid coordination body OCHA confirmed the report.