Aid groups have pulled resources from the fight against malnutrition to battle cholera in Yemen, raising the risk of famine as they struggle to find funds, a UN official said Thursday.

More than two years of war between Yemen's Saudi-backed government and Shiite rebels who control the capital has pushed the Arab world's poorest country to the brink of famine, the World Health Organization has warned.

But in April the country was hit by an outbreak of which it has struggled to contain as more than half of its medical facilities have been knocked out by the war.

Some 270,000 suspected cases have been registered and more than 1,600 people have died of cholera in just over two months.

"Humanitarian organisations have had to reprogramme their resources away from malnutrition and reuse them to control the ," the UN humanitarian coordinator in Yemen, Jamie McGoldrick, told a press briefing in the capital Sanaa.

"And if we don't get these resources replaced, then using those resources for cholera will mean that will suffer," he said.

McGoldrick said much of the $1.1 billion (981,500 euros) in aid pledged by donor governments in April to deal with the crisis had yet to be disbursed, leaving relief agencies struggling to find funds.

"We're trying to do our best, but it's very much beyond what we can cope with," he said.

The UN Office for the Coordination of Humanitarian Affairs has described Yemen as the "largest humanitarian crisis in the world".