The Yemeni people are suffering a "triple tragedy" as the country is ravaged by a brutal conflict, a cholera outbreak, and the threat of famine, the United Nations humanitarian chief said Friday.

The "vicious and brutal" war between the Saudi-backed Yemeni government and Iran-allied Houthi rebels is frequently conducted with complete disregard for international humanitarian law, Stephen O'Brien told the Security Council at a briefing in New York.There is no sign of improvement in the conflict, with number of air strikes per month now three times higher than last year and monthly reports of armed clashes up 50 per cent, he said.

The conflict, which has been ongoing since 2014, is a "deplorable, avoidable, completely man-made catastrophe that is ravaging the country," O'Brien said.

O'Brien and U.N. special envoy to Yemen Ismail Ould Cheikh Ahmed urged the Saudi-led coalition in Yemen to reopen Sana'a airport and allow humanitarian staff to enter the country quickly and Yemenis to leave to receive health treatment.

Despite international support for a peaceful settlement, certain parties in the conflict continued to "place personal interests ahead of the urgent need for peace," said Cheikh Ahmed, who briefed the Security Council via video link from Amman, Jordan.

The suffering of Yemenis has "relentlessly intensified," with 17 million who don't know where their next meal is coming from, nearly 7 million at risk of famine and nearly 16 million lacking access to water or sanitation, O'Brien said.

With a shattered healthcare system, Yemen is not able to cope with a major cholera outbreak that is now killing more people than the country's ongoing war. The cholera outbreak has wiped out the wreckage of what once the Yemeni healthcare system. With the rainy season approaching, there is a risk that cholera - which already kills more people every month than the violence itself - will multiply even faster, the U.N. warned earlier. The collapse of Yemen's infrastructure after more than two years of war between the Saudi-backed government and Iran-backed Houthis rebels who control the capital Sanaa has allowed the country's cholera epidemic to swell to the largest in the world. The WHO warned that the disease had spread rapidly due to deteriorating hygiene and sanitation conditions, with millions of people cut off from clean water across the country.

The WHO said that it and its partners were "working around the clock" to support the national efforts to halt the outbreak, adding that more than 99 percent of people who contract cholera in Yemen can survive if they can access health services. More than 15 million people in the country have no access to basic healthcare.

Two years of war between the Houthis and government forces backed by a Saudi-led military coalition have killed more than 8,000 people and wounded 45,000 others. According to the U.N. human rights agency, civilians account for nearly 5,000 of the recorded deaths and more than 8,500 of the injuries.