In a statement, Public Warehousing said its service had been "timely, reliable and cost-effective".
Public Warehousing, which is now called Agility Logistics, receives more than $1 billion a year to feed troops in Iraq and Kuwait.
The investigation, which was reported Wednesday in The Wall Street Journal, is also focusing on Army officials who picked the food companies that are Public Warehousing's suppliers.
Physicians for Human Rights, a relief group, says that officials demand ZANU-PF party cards from anyone registering for "food for work" schemes, as well as from those buying cheap maize from public warehouses.
Its width varies from about 100 to 225 feet (30 to 70 metres), and it is lined by buildings that once were the palaces of great merchant families and the public warehouses, or fondaci, used in foreign trade.
Procurement specialists said that once vendors like Public Warehousing received guidance from the Army Center of Excellence, Subsistence, at Fort Lee, Va., on what should be on the menu in chow halls, the vendors sought suppliers for that food.
But a Justice Department lawyer, Brian A. Mizoguchi, told a Federal Claims Court judge in Washington on June 12 that Public Warehousing's business arrangements were the target of "a very large and active investigation into criminal fraud involving amounts in the hundreds of millions of dollars".
Inside its air-conditioned public warehouses, there are about 1.5 million metric tons of imported rice, mostly from the United States, as a byproduct of global trade talks in the 1990s to open Japan's markets.
They provide for 29 distinct liquor licenses granted to manufacturers, wholesalers, retailers, and for the public warehousing and transport of alcoholic beverages.
