The U.N. World Food Program says it has suspended a food voucher program serving more than 1.7 million Syrian refugees because of a funding crisis.

The WFP says the program provided Syrian refugees in Jordan, Lebanon, Turkey, Iraq and Egypt with vouchers to buy food in local shops.

The U.N. agency said in a statement Monday that without the assistance "many families will go hungry."

WFP executive director Ertharin Cousin says the agency's Syria emergency operations are in critical need of funding — requiring $64 million to support Syrian refugees in December alone.

More than 3 million Syrians have fled the civil war in their homeland.