"The health sector in Yemen is working in impossible circumstances with the lack of potential," said , chief Tidros Ghanemis. He called on parties to the conflict in the war-torn country more than two years ago to reach a political solution urgently.
The World Health Organization , on Monday estimated that the cholera epidemic in Yemen has infected more than 500,000 people and killed some 2,000 since the end of April.
A WHO report providing an overview of the health situation in Yemen reported 503,484 possible infections and 1975 deaths linked to the outbreak of the epidemic four months ago in the war-torn country.
More than a quarter of deaths and more than 41% of potential child injuries, according to the UN Office for the Coordination of Humanitarian Affairs .
About 5,000 cases a day
The United Nations agency said the speed of the epidemic has declined markedly since the beginning of July, but warned that the water-borne epidemic still affects about 5,000 people a day.
The World Health Organization warned that the epidemic has spread rapidly due to deteriorating health conditions, with millions of Yemenis deprived of clean water.
"Health workers in Yemen are working in impossible conditions," said TEDROS chief executive officer Gibrousos.
"Thousands of people are sick, but there are not enough hospitals, medicines are not enough, clean water is not enough," he said, adding that doctors and nurses working to fight the outbreak have not been paid for nearly a year.
"Their salaries should be paid to continue saving lives."
The organization said it was working with partners "round the clock" to support national efforts to stem the spread of the disease, adding that more than 99% of cholera patients in Yemen can recover if they have medical services.
Basic medical services are not available to more than 15 million people in Yemen.
Tidros called on all concerned parties to the crisis in Yemen, which has killed more than 8,300 people since March 2015, to reach a political solution urgently.
"People in Yemen will not tolerate it for longer, they need peace to rebuild their lives and their country," he said.
Clashes between government forces backed by Saudi Arabia and Shi'ite militias backed by Iran have destroyed most of the infrastructure and allowed cholera to spread to this point.