The World Food Programme (WFP) has been forced to suspend a critical food aid scheme for more than 1.7 million Syrian refugees because of a funding crisis.
The UN agency said the programme gave refugees in Jordan, Lebanon, Turkey, Iraq and Egypt vouchers to buy food.
Without such assistance, many families would go hungry this winter, it warned.
The WFP's Executive Director, Ertharin Cousin, said it was in critical need of funding, with $64m (£41m) required to support refugees in December alone.
More than 3.2 million people have fled Syria and another 7.6 million have been displaced inside the country since the uprising against President Bashar al-Assad began three years ago.