War-torn Yemen is suffering from a cholera outbreak, the UN's children agency said Friday, posing a further threat to infants in the impoverished nation. "This outbreak adds to the misery of millions of children in Yemen," UNICEF Yemen representative Julien Harneis said in a statement. "Children are at a particularly high risk if the current cholera outbreak is not urgently contained especially since the health system in Yemen is crumbling as the conflict continues." UNICEF said health professionals in the rebel-held capital Sanaa had reported several cases, as had medics in Taiz, Yemen's third largest city. It said its team was working with doctors in Yemen to establish the cause of the outbreak and called on international donors to provide funding to work to improve the health situation there. UNICEF said that cholera, a disease that is transmitted through contaminated drinking water and causes acute diarrhea, could prove fatal in up to 15 percent of untreated cases. The agency says nearly three million people in Yemen are in need of immediate food supplies, while 1.5 million children suffer malnutrition, including 370,000 enduring very severe malnutrition that weakens their immune system. The UN says more than 6,700 people have been killed and more than three million displaced by fighting in Yemen since March 2015, when the coalition launched its campaign.