The U.N.'s World Food Program says unknown assailants in Syria have carried out at least 20 attacks on its food trucks, warehouses and cars since emergency operations were launched in December 2011.
WFP spokeswoman Elisabeth Byrs says no one was hurt or killed in the attacks, but she could not provide more details on locations or attackers.
Byrs told reporters Tuesday in Geneva that the attacks show "it's becoming more and more difficult with this growing violence to reach the people who are in need of assistance."
The U.N.'s food agency says 2.5 million people in Syria and almost 1 million refugees in neighboring countries need its help, costing $19 million a week.
A U.N. panel estimated in mid-February that at least 70,000 people have died in Syria's 2-year-old conflict.