Countries are expected to spend $1.8 trillion to import the food they need this year; this would be a new world record but worryingly, it is going to buy them less food, not more, according to the UN Food and Agriculture Organization (FAO).

Ever-higher fixed costs for farmers of "agricultural inputs" such as fertiliser and fuel are likely to be responsible for this year's bigger-than-ever global food import bill, the FAO said Thursday in its latest Food Outlook report.

All but $2 billion of the additional $51 billion that is going to be spent worldwide on edible imports this year was owing to higher prices, the UN agency said. "Animal fats and vegetable oils will be the single biggest contributor to higher import bills this year, although cereals are not far behind for developed countries. Developing countries, as a whole, are reducing imports of cereals, oilseeds and meat, which reflects their incapacity to cover the increase in prices."

Read: FAO records small drop in global food prices in April

Among the most vulnerable nations, the FAO estimated that least developed countries will have little option but to spend five percent less to import food this year.

The sub-Saharan African states and other nations that buy more food than they export are likely to face an increase in costs, for which they will get lower amounts of essential foodstuffs.

"These are alarming signs from a food security perspective. Also, importers will find it difficult to finance rising international costs, and these could, potentially, break them," the FAO said.

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To help avoid greater food insecurity among low-income nations and to guarantee food imports, the UN agency has recommended the creation of a balance-of-payment support mechanism.