Mogadishu, Somalia ? Sacks of grain, peanut butter snacks and other food staples meant for starving Somalis are being stolen and sold in markets, an Associated Press investigation has found, raising concerns that thieving businessmen are undermining international famine relief efforts in this nearly lawless country.

The U.N.’s World Food Program acknowledged for the first time that it has been investigating food theft in Somalia for two months. The WFP strongly condemned any diversion of “even the smallest amount of food from starving and vulnerable Somalis.”

Underscoring the perilous security throughout the food distribution chain, donated food is not even safe once it has been given to the hungry in the makeshift camps popping up around the capital of Mogadishu. Families at the large, government-run Badbado camp, where several aid groups distribute food, said they were often forced to hand back aid after journalists had taken photos of them with it.

“They tell us they will keep it for us and force us to give them our food,” said refugee Halima Sheikh Abdi. “We can’t refuse to cooperate because if we do, they will force us out of the camp, and then you don’t know what to do and eat. It’s happened to many people already.”

The U.N. says more than 3.2 million Somalis — nearly half the population — need food aid after a severe drought that has been complicated by Somalia’s long-running war. More than 450,000 Somalis live in famine zones controlled by al-Qaida-linked militants, where aid is difficult to deliver. The U.S. says 29,000 Somali children under age 5 already have died.

International officials have long expected some of the food aid pouring into Somalia to disappear. But the sheer scale of the theft calls into question the aid groups’ ability to reach the starving. It also raises concerns about the ability of aid agencies and the Somali government to fight corruption, and whether diverted aid is fueling Somalia’s 20-year civil war.

“While helping starving people, you are also feeding the power groups that make a business out of the disaster,” said Joakim Gundel, who heads Katuni Consult, a Nairobi-based company often asked to evaluate international aid efforts in Somalia. “You’re saving people’s lives today so they can die tomorrow.”

For the past two weeks, planeloads of aid from the U.N., Iran, Turkey, Kuwait and other countries have been roaring into Mogadishu almost daily. Boatloads more are on the way. There is no doubt that much of it is saving lives: the AP saw hungry families lining up for hot meals at feeding centers, and famished children eating free food while crouched among makeshift homes of ragged scraps of plastic.

WFP Somalia country director Stefano Porretti said the agency’s system of independent, third-party monitors uncovered allegations of possible food diversion. But he underscored how dangerous the work is: WFP has had 14 employees killed in Somalia since 2008.

“Monitoring food assistance in Somalia is a particularly dangerous process,” Porretti said.

In Mogadishu markets, vast piles of food are for sale with stamps on them from the WFP, the U.S. government aid arm USAID, the Japanese government and the Kuwaiti government. The AP found eight sites where thousands of sacks of food aid were being sold in bulk. Other food aid was also for sale in numerous smaller stores. Among the items being sold were Kuwaiti dates and biscuits, corn, grain, and Plumpy’nut — a fortified peanut butter designed for starving children.

An official in Mogadishu with extensive knowledge of the food trade said he believes a massive amount of aid is being stolen — perhaps up to half of recent aid deliveries. The percentage had been lower, he said, but in recent weeks the flood of aid into the capital with little or no controls has created a bonanza for businessmen.

The official, like the businessmen interviewed for this story, spoke on condition of anonymity to avoid reprisals.

The AP could not verify the official’s claims. WFP said that it rejected the scale of diversions alleged by the official.