The director of the UN's World Food Programme has said it is considering plans to ration food aid because of rising prices and a shortage of funds.

Josette Sheeran told the BBC that the WFP needed increased contributions from donors to make sure it could meet the needs of those who already rely on it.

She said it also faced growing demands from countries like Afghanistan, where people were now unable to afford food.

Food prices rose 40% last year because of rising demand and other factors.