LES CAYES (Reuters) - Haitians on Thursday protested against the death of a motorcyclist in an accident they blamed on blue-helmeted peacekeepers, adding to a spate of incidents the United Nations says is affecting delivery of relief after Hurricane Matthew.The category 4 hurricane tore through Haiti on Oct. 4, killing about 1,000 people and leaving more than 1.4 million in need of humanitarian aid, including 175,000 made homeless, besides disrupting power, communications and transport links.

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An international relief effort headed by the Haitian government has accelerated this week, but tempers are running high across the hard-hit southwest because help has yet to reach many families whose crops and water supplies were destroyed, increasing the risk of cholera and malnutrition.

On Thursday, near the coastal town of Saint-Jean-Du-Sud, about 100 people gathered around the corpse of a motorcyclist they said was hit by a truck in a convoy of U.N. peacekeepers.

“MINUSTAH killed Jean-Claude,” one woman shouted, using the acronym for the U.N. mission based in the country since 2004.

A Brazilian contingent of U.N. peacekeepers and Haitian national police held back the crowd until an ambulance arrived. Men pulled downed trees across the road to barricade it briefly.

“Debris from the hurricane has not been removed and it encourages accidents,” said Dieuleme Boulote, 40, a journalist for Radio Lumiere, who added that he did not blame the U.N. mission. “The government is supposed to unblock the road.”

Efforts are being made to clear roads and deliver aid, especially to tackle cholera, a disease accidentally brought to the country by U.N. peacekeepers six years ago.

The armed peacekeepers are accompanying convoys because of cases of looting and attacks on aid trucks.

Stephane Dujarric, a spokesman for U.N. Secretary-General Ban Ki-moon, said there had been several security incidents involving humanitarian aid, including one in which peacekeepers fired their weapons.

“On 11 October, U.N. escort troops fired non-lethal ammunition to disperse crowds attempting to loot a humanitarian convoy in Les Cayes,” said Dujarric, speaking before Thursday’s protest.

On Saturday, he added, Ban would be in Les Cayes, a port town badly hit by the storm.

The United States Agency for International Aid (USAID) announced $12 million in additional humanitarian aid, including 515 tonnes of items such as blankets and chainsaws airlifted by the U.S. military. Venezuela said it had sent 700 tonnes of aid material by ship.

USAID said $7 million would go toward the U.N. World Food Program for food assistance, with $2 million going to improve logistics and telecommunications, and the rest for relief supplies.