A U.S. official on Monday accused Venezuela's President Nicolas Maduro of "rapacious corruption" and operating "a kleptocracy" on a rarely seen scale that includes not only embezzling from the state-owned oil company but stealing from a government program created to feed millions of hungry people.

Marshall Billingslea, the U.S. Treasury's assistant secretary for terrorist financing, alleged at an informal meeting of the U.N. Security Council that corruption by Maduro, his wife Celia Flores and their inner circle "have laid low a once great nation, and impoverished millions."

The result, he said, is "a humanitarian crisis threatening regional stability," a near-collapse of Venezuela's oil production, and an economy "now in a death spiral."

U.S. Ambassador Nikki Haley, who organized and chaired the meeting, said widespread corruption in Venezuela has unleashed "instability, violence and human misery."

She said Venezuela's late president Hugo Chavez's "perverse vision of a socialist paradise in Venezuela has transformed into a criminal narco-state that is robbing the Venezuelan people blind."

"Something is very wrong when citizens of an oil-rich country have to leave in order to beg on Colombian streets to feed their children," Haley said. "That something is the corruption of the Maduro regime."

Venezuela's U.N. Mission did not send a representative to the open meeting and the mission had no comment on it.

Maduro regularly blames Venezuela's shortages and inflation on an economic war waged by the United States and other capitalist powers. Venezuelan authorities also accuse opponents of sounding an alarm about a humanitarian crisis to justify a foreign military intervention.

Venezuela was once among Latin America's most prosperous nations, holding the world's largest proven oil reserves, but a fall in oil prices accompanied by corruption and mismanagement under two decades of socialist rule have left the economy in a historic economic and political crisis.

Inflation this year could top 1 million percent, according to economists at the International Monetary Fund.

Billingslea said "the cumulative effective of theft" from state-owned Petroleos de Venezuela has resulted in a more than 70 percent drop in oil export revenues since 2012.

And as the oil sector has plummeted, he said, "regime insiders are now jockeying to loot another of Venezuela's precious natural resources, its gold deposits."

Billingslea said the collapse in oil revenue led to a collapse in the Maduro government's ability to import food, medicine and other goods — and he accused regime officials of illegally profiting at every stage of the government-controlled program that was started to distribute food.

This includes "at the end when they replaced more valuable or popular food products, such as dry milk with lower value, mass-produced products," Billingslea said.

"The valuable products are then sold on the black market at high profit margins for officials' personal enrichment," he said. "For example, an investigation by Venezuela's democratically elected National Assembly uncovered instances where the regime spent $42 for a box of food when the food items in the box cost less than $13. Maduro's inner circle kept the difference, which amounted to over $200 million in just one particular order."

Stressing that more than half of Venezuela's population now lives in "extreme" poverty, Billingslea urged U.N. member states to hold the regime to account and investigate individuals under sanctions from the U.S. — including Maduro — as well as the European Union and others, and freeze their assets and prevent their travel.