A U.N. humanitarian aid official says a 72-hour pause in fighting between Yemen's warring sides is a welcome first step, but is urging longer-term access.

OCHA's Jamie McGoldrick says Yemen's economy has all but collapsed, damage to a key port has hindered deliveries of food, goods and aid, only about half of hospitals are even partially operating and a cholera outbreak that began three weeks ago could spread.

With a 72-hour truce to take effect before midnight Wednesday, McGoldrick told reporters in Geneva by phone that OCHA will focus on reaching previously inaccessible "pockets" of the frontline city of Taiz during the truce.

He cited a "stalemate" in the war, lamented a shortfall in international aid funding, and said Yemen's war gets less media attention than Iraq and Syria.