A lack of funds has forced the United Nations to stop providing food vouchers for 1.7 million Syrian refugees in Jordan, Lebanon, Turkey, Iraq and Egypt, the World Food Program said on Monday.

"Without WFP vouchers, many families will go hungry. For refugees already struggling to survive the harsh winter, the consequences of halting this assistance will be devastating," said the U.N. agency, which needs $64 million to support the refugees for the rest of December.

Suspension of the assistance program comes as many vulnerable Syrian families enter their fourth bleak winter in difficult living conditions after fleeing a homeland racked by conflict since March 2011.