(CNN) -- The supply line to Haiti is clogged by airport congestion and blocked roads, forcing thousands of earthquake survivors to scrounge for food and emergency aid. But the head of the United Nations is calling for calm among the increasingly desperate populations.
"I know that there is a frustration amongst Haitian people, but when I met them, from their faces, I have seen that they have great hope and they are a great, resilient people," U.N. Secretary-General Ban Ki-moon told CNN's Christian Amanpour in an exclusive interview Monday.
Ban visited the impoverished island nation -- the poorest in the Western Hemisphere -- over the weekend. "I told them that to be more patient, because [the] whole world [is] standing behind them."
But that is easier said than done, as spurts of violence and looting have popped up in the capital of Port-au-Prince and elsewhere. Millions of dollars of aid are pouring into Haiti, but aid workers are struggling to deliver the food and supplies nearly a week after the devastating 7.0-magnitude earthquake struck January 12.
On Sunday, Ban said, "We cannot waste one minute, one dollar and one person. We cannot have vital supplies sitting in warehouses."
Still, victims are running out of patience, fueling tensions in the streets and confrontations with local police.
iReport: People continue to look for loved ones
"We don't have anything to eat. ... We don't even have some water to drink," one woman said. "It's a big problem, so we need -- we need food. We need something to drink. I'm speaking to you. I am hungry. I need food. I need something -- I need some water to drink."
Ban acknowledged in the Amanpour interview Monday that the United Nations is playing the primary role in coordinating the aid effort.
"We are now trying to create [a] structured system to effectively ... deliver this assistance to needy people. We should not waste even a single dollar, single item of relief," he said.
However, Ban couldn't give a timeline for how long it will take to get the abundance of aid collected for Haiti flowing freely into the country.
"We are in an initial stage of this, coordinating and organizing [an] effective way of delivering aid, and we have to work for ... recovery, bringing in all this water supply and sanitation and power supply and communications, that we have to work for middle, longer-term reconstruction," he told Amanpour.
"We need at least to feed 2 million people in about a [month's] time. The United Nations World Food Programme is going to provide and feed 2 million people in about a month. ... Maybe within 15 days, we will feed 1 million people," he added.
Ban also addressed concerns about safety, especially after reports of doctors leaving field hospitals at night due to a lack of security on the ground. The United Nations has about 9,000 peacekeepers in Haiti, a third of them in Port-au-Prince.
Ban said he has requested that the U.N. Security Council increase levels by another 3,500 "to take charge of all this security, to help humanitarian assistance be delivered in a safe way."
The United Nations has lost at least 46 personnel in the disaster, the greatest single loss for the world body in its history, the secretary-general said. That includes the top two civilian officials at the U.N. mission in Haiti
"Yesterday, when I came back from Haiti, I brought the remains of my special representative, Hedi Annabi, and his deputy," Ban said. "It was a heartbreaking experience for me."