Yemen cholera epidemic: Cases exceed 500,000 in four months

Media captionWatch: The reality of life in Yemen

The WHO said shortages in medicines and supplies were persistent and widespread, and that 30,000 health workers had not been paid in almost a year.

"Yemen's health workers are operating in impossible conditions," said the WHO's director general, Dr Tedros Adhanom Ghebreyesus.

"Thousands of people are sick, but there are not enough hospitals, not enough medicines, not enough clean water.

"These doctors and nurses are the backbone of the health response - without them we can do nothing in Yemen. They must be paid their wages so that they can continue to save lives."

The WHO's director of emergency operations, Rick Brennan, meanwhile told the BBC that despite the "downward trend" in the number of cases, the rainy season might result in "spikes" during August and September.

Dr Tedros called on all sides in Yemen's conflict, which has killed more than 8,160 people and injured 46,330 since March 2015, to urgently find a political solution.

"The people of Yemen cannot bear it much longer - they need peace to rebuild their lives and their country," he added.