World leaders are ignoring potentially disastrous shortages of key crops, and their failures are fuelling political instability in key regions, food experts have warned.

Food prices have hit record levels in recent weeks, according to the United Nations, and soaring prices for staples such as grains over the past few months are thought to have been one of the factors contributing to an explosive mix of popular unrest in Egypt and Tunisia.

The crises in those countries have served as a stark example of what can happen when food prices spiral out of control and add to existing political problems, said Lester Brown, founder of the Earth Policy Institute. "It's easy to see how the food supply can translate directly into political unrest," he said.

Richard Ferguson, global head of agriculture at Renaissance Capital, an investment bank specialising in emerging markets, said the problems were likely to spread. "Food prices are absolutely core to a lot of these disturbances. If you are 25 years old, with no access to education, no income and live in a politically repressed environment, you are going to be pretty angry when the price of food goes up the way it is."

He said sharply rising food prices acted "as a catalyst" to foment political unrest, when added to other concerns such as a lack of democracy.

While food was not the biggest cause of the Middle East protests, there has been widespread discontent over rampant food price inflation that has left millions of poor families struggling to find enough to eat. Egypt is the world's biggest importer of wheat.

The UN's Food and Agriculture Organisation said this week that world food prices hit a record high in January, for the seventh consecutive month. Its food price index was up 3.4% from December to the highest level since the organisation started measuring food prices in 1990.

Cereal prices are still about 10% below the peak they hit in April 2008, but have risen about 3% in the past month, after problems with last year's harvests caused by fires in Russia and bad weather.

A poor harvest this year would be catastrophic, said Brown, as global grain reserves are unusually low at present.

Brown warned that the longer term outlook was also bleak. Many arid countries have managed to boost their agricultural production by using underground water sources, but these are rapidly drying up. He cited Saudi Arabia, which has been self-sufficient in wheat for decades but whose wheat production is collapsing as the aquifer that fed the farms is depleted.

Water scarcity, combined with soil erosion, climate change, the diversion of food crops to make biofuels, and a growing population, were all putting unprecedented pressure on the world's ability to feed itself, according to Brown. This would fuel political instability and could lead to unrest or conflicts, he said. "We have an entirely new situation in the world. We need to recognise this."

Richer countries such as China and Middle Eastern oil producers have reacted by buying up vast tracts of land in poorer parts of the world, such as sub-Saharan Africa and parts of south-east Asia.

Rising food prices in the next few months could trigger a wave of reactions from governments that would exacerbate the current problem, argued Maximo Torero, of the International Food Policy Research Institute. "The big danger is that you get political pressure on countries to put in place restrictions on food, such as export bans on grains. We need to be very careful, as the situation is very tight and any additional pressure could take us to a very similar position to the one we had in 2007 and 2008."

There were widespread food riots in 2008 in Africa, Latin America and some Asian countries, as soaring grain prices put staple foods out of reach of millions of poor people.

Camilla Toulmin, director of the International Institute for Environment and Development, urged politicians to begin to tackle some of the root causes of food insecurity. "It's not surprising that you are seeing people coming out on to the street to protest, given the price rises. You are going to see a lot more of this unless governments start addressing the fundamentals, such as climate change, water scarcity and dependence on oil. We need to create more resilient systems of agriculture for the future."

The problem could not be more urgent, added Brown, who warned that politicians around the world had ignored food security and water scarcity for years. "We are quite literally on the edge of chaos. Whether we can draw back from the edge, and create food price stability – I don't know."