UN Secretary General Ban Ki-moon voiced distress Saturday at the "absolute devastation" caused by a deadly hurricane in Haiti, and disappointment at scant emergency aid reaching the struggling nation.

"I am disappointed by the response of the international community. I sincerely hope and I urge the major donors to lend their helpful hand," Ban said at Port-au-Prince airport following a helicopter overflight of the hard-hit southern regions.

Haiti is only just emerging from the devastating aftermath of a January 2010 earthquake that killed more than 200,000 people. The international aid that poured in at the time, poorly coordinated, became a major fiasco, with only a fraction of the funds reaching the victims of the catastrophe.

"I know there is some fatigue from certain countries, but the current situation, the current disaster that hit this country through Hurricane Matthew is beyond description," Ban said during a joint press conference with interim president Jocelerme Privert.

At least 546 people were killed, and more than 175,000 people have lost their homes.

Ban said Monday that a "massive response" was needed to cope with the destruction, with 1.4 million people in need of urgent assistance after towns and villages were almost wiped off the map.

The United Nations has launched a flash appeal for $120 million to help Haiti, the poorest country in the Western Hemisphere, cope with its worst humanitarian crisis since a devastating 2010 earthquake.

But so far, only about 12 percent of the needed funds has been raised to help stave off famine and serious health crises, including cholera.

- 'Very, very sad' -

Privert, the interim leader, called for long-term support from allies.

"There will always be hurricanes, there will always be catastrophes. We need concrete actions to mitigate the damage from the next hurricanes that have not hit yet," Privert said.

Earlier, Ban visited Les Cayes, one of the worst affected by Hurricane Matthew when it crashed ashore on October 4, packing winds of 145 miles (230 kilometers) per hour.

"I was very, very sad when we saw the complete devastation. But people the world over stand with you," the UN chief said, speaking in French.

"The United Nations stands by your side. We will mobilize all resources to help you."

The streets have been cleaned. The branches and tree trunks form massive heaps on the sidewalks. Businesses have reopened.

Ban was warmly received at Philippe Guerrier high school, where more than 500 people are still huddled. He spoke with a young man who was wounded, before telling the displaced: "kembe fem" in Creole ("hang in there").

"We have been told to leave because school has to start again, but we don't have anywhere to go," said Aivi Jean-Bar.

"They bring us a bit to eat and drink, but that's not what we need. What we want to know is where we can go to sleep," the 36-year-old woman sheltering at the school with her four children told AFP.

- Cholera on the rise -

In addition to the destruction of countless homes and farms, Haitians in the worst-affected areas are dealing with a lack of potable water, which is contributing to the spread of disease.

Haiti has been plagued for half a dozen years by cholera, which has claimed close to 10,000 lives, despite extensive efforts to combat it

The malady was brought to Haiti by UN peacekeepers from Nepal, who were helping in the aftermath of the earthquake.

Officials have seen evidence of a new spike in cholera cases, which prompted the World Health Organization last week to announce it was sending an additional one million doses of vaccine to Haiti.

The UN Security Council, meanwhile, agreed earlier this week to extend MINUSTAH's stay until April of next year to help combat the myriad crises in the aftermath of Matthew.

The hurricane also prompted election officials to push back already delayed presidential and legislative elections until November 20.

The elections are a do-over after an earlier vote had to be annulled because of violence and massive fraud.