A closure of the last aid corridor from Turkey into northwest Syria’s rebel-held areas would spell “catastrophe” for millions of people, a UN aid official has warned. “This is one of the most vulnerable populations anywhere in the world,” said Mark Cutts, UN deputy regional humanitarian coordinator for the Syria crisis. “It is absolutely essential that we keep this lifeline going.” Cutts spoke ahead of a UN Security Council vote to renew the world body’s authorisation to deliver assistance through the Bab al-Hawa crossing before its mandate expires on July 10. More than 4,600 aid trucks, carry…