"This cholera scandal is entirely man-made by the conflicting parties and those beyond Yemen's borders who are leading, supplying, fighting and perpetuating the fear and fighting," Stephen O'Brien told the UN Security Council.
The humanitarian crisis "is a direct result of the conflict and serious violations of international law," he said.
More than 3,20,000 suspected cholera cases have been reported in nearly all of Yemen's districts and at least 1,740 people have died from the outbreak, said O'Brien, the UN under-secretary-general for humanitarian affairs.
More than seven million people are at risk of famine including 2.3 malnourished children under the age of five in Yemen, already among the Arab world's poorest countries.
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Yemen's health system has collapsed during the war pitting the Saudi-led coalition backing the internationally recognized Yemeni government and Iran-backed Shiite Huthi rebels since March 2015.
The Huthi rebels still hold the capital Sanaa and Taez, the country's third largest city.
He also urged council powers to take action to ensure public servants are paid so that health facilities can reopen.
The airport in Sanaa, which closed last year, must be reopened and the port of Hodeida, a crucial lifeline for deliveries of food and medicine, must be kept safe from attack, O'Brien said.
The aid chief urged Saudi Arabia to allow mobile cranes left in Dubai to arrive at Hodeida port.
Riyadh has accused the Huthi rebels of using the port to smuggle weapons into the country.