The United Nations' food agency said Tuesday that 600,000 Syrians could not receive aid this month as spiralling violence prevented convoys from reaching them.
Elisabeth Byrs, spokeswoman for the World Food Programme, told reporters that the agency had aimed to reach a total of three million people in Syria in July, but had succeeded in getting supplies to only 2.4 million.
"Rising violence in many parts of Damascus and Homs, and a proliferation of checkpoints around the main cities have hit the flow of food distribution," she said.
The number fed in July was also lower than the 2.5 million Syrians the WFP helped in June.
Byrs said that the WFP's operations inside Syria and for refugees in neighbouring countries cost just over $29 million (22 million euros) per week.
She said that without further donations, the agency faced a shortfall of $763 million by the end of the year.