UN secretary-general Ban Ki-moon has visited victims of devastating Hurricane Matthew, saying the destruction wrought by the storm was "heartbreaking".
He renewed a pledge to help the nation cope with a deadly scourge of cholera that was introduced by UN peacekeepers.
Ban's brief visit came as victims of the storm continued to express frustration - sometimes violently - at delays in aid about a week and a half since Matthew hit south-west Haiti with 145 mph winds, killing at least 546 people and demolishing or damaging tens of thousands of homes.
"I met so many displaced persons, young people, women who were pregnant and sick people. It was heartbreaking," he said, describing his tour of an emergency shelter in the town of Les Cayes packed with families whose homes were destroyed.
Shortly before Ban's helicopter was due to land in Les Cayes, a clash broke out between rock-throwing residents and peacekeepers at a UN base there.
Roughly 100 frustrated residents began hurling rocks when trucks ferrying food aid arrived. Haitian police officers and UN peacekeepers scattered the group with tear gas. Calm was restored as Ban's helicopter approached.
In recent days, reporters have observed a number of skirmishes between Haitians in hard-hit areas seeking emergency aid distributed by international and local organisations.
At the close of his roughly four-and-a-half-hour stop in Haiti, Mr Ban told reporters at Port-au-Prince's airport that a cholera-focused trust fund announced in recent weeks was part of the UN's "new approach" to helping Haitian families who lost loved ones since the water-borne disease was introduced there in October 2010 - an outbreak that has been aggravated by the hurricane.
The UN said the fund is designed to help Haiti overcome cholera and build stronger water, sanitation and health systems.
There has long been ample evidence that cholera was introduced to the nation's biggest river by inadequately treated sewage from a UN peacekeeping base about 10 months after Haiti's devastating earthquake.
But the UN only acknowledged in August, following a leaked internal report, that it played a role in introducing cholera to Haiti and vowed to aid victims in the impoverished Caribbean nation, which has experienced the worst outbreak of the disease in recent history.
UN deputy spokesman Farhan Haq said that "the United Nations has a moral responsibility to the victims".
Mr Ban expressed disappointment that international funding to fight cholera in Haiti and rebuild after Matthew is so far falling far short.
"I know that the world economic situation is not favourable, and I know that there is some donor fatigue by certain countries," he told reporters at the close of his brief visit.
Health authorities say they have been struggling with a surge of patients with cholera in the wake of the storm that struck on October 4 in a rugged region of south-west Haiti that is home to more than one million people.
The wreckage left behind by the hurricane has created perfect conditions for spreading the disease. Rivers and outdoor toilets overflowed across the mountainous landscape.