People in some developing countries are paying nearly four times their weekly salary on food shopping, according to Save the Children.
The charity asked staff in nine countries to buy a variety of food from local markets such as meat, bread, oil, milk, fruit and vegetables.
Shopping online at a major supermarket in the UK, the basket of food would cost £7, the charity said.
But in South Sudan, the basket cost nearly four times the average salary, and was the equivalent of paying £1,838 for the food in the UK.
In Somaliland, it cost twice the local average weekly salary, the equivalent of £1,034 in the UK.
In India the basket cost half of the average weekly salary, equivalent to £270, whilst in Mozambique the equivalent of £490 pounds, Ivory Coast £200, Egypt it was £167, Bangladesh £161 and Spain £20.
Record food prices in 2011 put an additional 400,000 children's lives at risk. Justin Forsyth, Save the Children
The charity stressed that the survey, carried out to coincide with World Food Day, was not scientific. But it pointed out that in some countries meat, fish or bread are already too expensive to be considered part of a regular daily or even weekly diet.
The charity warned that record food prices in 2011 put an additional 400,000 children's lives at risk and led to food riots globally.
Justin Forsyth, Save the Children's chief executive said: "Even before food prices started to rise, many poor parents were struggling to afford nutritious food for their children.
"When prices rise, families cut back even further - unable to pay the price of nutritious foods which will help children grow up healthy and fulfil their potential. The slow progress globally on malnutrition - still the underlying cause of a third of child deaths - could be at risk if we don't act to help the poorest families."
Read more: Why are food prices set to rise?
In July this year maize and wheat increased by 25 per cent globally - but rises are much sharper in some developing world countries.
In Malawi, maize increased by 174 per cent, in Mozambique by 129 per cent and by 52per cent in Sudan between July 2011 and July 2012, according to the charity.
The charity called for world leaders to urgently boost funding for agricultural work as well as for the stockpiling of reserves of food in high risk areas.
It also called on countries, particularly Russia, "not to panic" and set export bans which would raise prices further.
Mr Forsyth continued: "Record food prices in 2011 put an additional 400,000 children's lives at risk and led to 30 food riots globally. Without the right food, children can suffer chronic malnutrition, growing up permanently physically and mentally impaired. The world must wake up to this crisis and urgently move to protect children."
Where possible, the charity used World Bank estimates of countries' average salaries for the survey. For South Sudan, none was available so they used an estimate from the UN's Office for the Co-ordination of Humanitarian Affairs.