Wheat
© Reuters / Todd KorolAn ear of wheat is seen on the Canadian prairies near Lethbridge, Alberta, September 7, 2011.

London - Soaring food costs are forcing some children to eat hay and leaves because their parents cannot afford to put food on the table, according to Save the Children.

The aid agency said its research showed that recent price hikes had put 400,000 children at risk.

It called for world leaders meeting at the G20 summit in Cannes this week to keep their funding promises for agriculture in order to ensure children are protected from rising food costs.

Barely a fifth of the $22 billion pledged in 2009 to help the world's poorest farmers over a three-year period has been disbursed, according to the latest available figures.

Eleven of the 13 countries behind this promise - made at the G8 summit in Italy - will be among those meeting in the French city of Cannes from Nov. 3-4.

But the aid agency said it feared the euro zone crisis could squeeze the global food crisis off the G20's agenda.

"Rising food prices are making it impossible for some families to put a decent meal on the table. The G20 must use this summit to agree an action plan to address the food crisis ...," said Brendan Cox, Save the Children's policy and advocacy director.

Malnutrition contributes to nearly a third of child deaths. One in three children in the developing world are stunted, leaving them weak and less likely to do well at school or find a job.

Prices of staples like rice and wheat have increased by a quarter globally and maize by three quarters, Save the Children says.

Some countries have been particularly hard hit. In Bangladesh the price of wheat increased by 45 percent in the second half of 2010.

In new research, Save the Children analysed the relationship between rising food prices and child deaths. It concluded that a rise in cereal prices - up 40 percent between 2009 and 2011 - could put 400,000 children's lives at risk.

The G20 is the main forum for international economic cooperation made up of 19 countries and the European Union. It accounts for 85 percent of global gross domestic product and two-thirds of the world population.