Elisabeth Byrs, spokeswoman for the World Food Program, told reporters on Tuesday 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.
Byrs said that the WFP's operations inside Syria and for refugees in neighboring 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.
People are trapped in many parts of Syria by foreign-backed insurgents and radical groups, especially in Aleppo and Homs provinces.
They usually use people as human shields to stop the army enter occupied areas.
Extremist groups, who have received fresh packs of arms and ammunition from their supporters, have been launching bloody offensives in different parts of the country, killing hundreds of civilians and Syrian soldiers.
The violence goes on as the United States and its Western and regional allies have not retreated from their strong political and military support to the insurgents, despite the fact that most of them are now radical and terrorist groups who control the war.
A massacre of 123 people in the town of Khan al-Assal in Aleppo, drew fierce criticism from Russia, calling on all sides responsible for the crime to stop the carnage.
Al-Nusra Front and Ansar al-Khilafah groups, strongest armed groups in Syrian opposition’s bloody insurgency against the government, claimed responsibility for the attack.
The war in Syria started in March 2011, when pro-reform protests turned into a massive insurgency following intervention of western and regional states.
The unrest, which took in terrorist groups from across Europe, the Middle East and North Africa, has transpired as one of the bloodiest conflicts in recent history.
As the foreign-backed insurgency in Syria continues without an end in sight, the US government boosts its political and military support to Takfiri extremists.
Washington has remained indifferent about warnings by Russia and other world powers about the consequences of arming militant groups.
SHI/SHI