Maurer warned that the unprecedented outbreak of cholera was "alarming and growing".
Arriving in the government-controlled city of Aden on Sunday Peter Mauer warned that the "great tragedy is that this cholera outbreak is a preventable, man-made humanitarian catastrophe", adding that he found the "needless suffering absolutely infuriating".
He explained that devastation of Yemen's health system and infrastructure by the ongoing civil war is directly responsible for the health crisis.
Worldwide human rights organisation CARE has denounced the humanitarian crisis in war-torn Yemen, which is also suffering from a cholera epidemic, as "an absolute shame on humanity".
The war in Yemen has caused more than 8 000 deaths - mostly of civilians - since the coalition intervened, according to the World Health Organisation (WHO).
World Health Organization has most recently reported 368,207 suspected cholera cases, and 1,828 deaths due to the disease since April.
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As of late Sunday, two men remain trapped on a ledge on the far side of the canyon, according to the rescue association. Gress said this isn't the first time his department has seen this type of situation this year.
The war has also put the country on the verge of starvation, a situation that can aggravate the danger of cholera because the outcome is usually more critical for malnourished people.
Over 3 million people have fled their homes since the onset of the conflict, and more than 20 million are in need of humanitarian assistance throughout the country.
A couple of weeks ago, ICRC doubled its aid to the struggling Arab country, Maurer told Al Jazeera.
Yemen's rainy season from July to September would increase the risk of the disease spreading further through water contaminated with faeces, Oxfam has said.
The UN representatives declined to elaborate on the visit, however, Yemen's official Saba news agency said the officials had met self-styled prime minister Ahmed bin Dagher for talks on global humanitarian aid, adding that the visit aimed to contain "the cholera epidemic which has spread to all provinces". Frequent consumption of uncontaminated water and food can effectively treat the disease, but without treatment it can prove fatal.
Cholera infection first became epidemic in Yemen last October and spread until December, when it dwindled.