The world food market is still "seriously exposed" to speculators artificially driving up prices and worsening the risks of malnutrition, according to one of the world's leading agricultural researchers.

Linking the recent food and financial crises, Joachim von Braun, the head of the International Food Policy Research Institute (IFPRI), warned that the world was at risk of a new panic over grain unless commodity markets were more tightly regulated and production expanded.

"The banking sector is in the process of being re-regulated worldwide, but the food market remains seriously exposed to short-term flows of indexed funds into commodity exchanges. That vulnerability needs to be addressed," he said in an interview with the Guardian.

Von Braun was one of the first to predict the sharp rise in food prices that peaked last year, when 13 nations halted cross-border trade amid fears of shortages.

The crisis, which escalated over four years, hit poor people hardest and saw pasta protests in Italy, tortilla rallies in Mexico and onion demonstrations in India.

During that period, the UN's Food and Agriculture Organisation estimates the number of hungry people in the world rose from about 800 million to more than 1 billion.

At the time, most of the blame for the price spike centred on growing populations, climate change, biofuels, rising oil prices and increased demand from fast-growing economies like China and India that were running down food stocks.

But von Braum said recent research highlighted the role of commodity speculators: "What we didn't foresee two years ago is how speculation exacerbated the real market issues. It was not a primary cause but a second-round amplifier, which added seriously to the problem."

Daily trading volumes on the Chicago commodities exchange surged at the peak of the crisis between December 2007 and March 2008, boosted by the entry of non-commercial investors entering the market to speculate.

"When food supply is at risk, speculators are attracted, especially when trade barriers are put in place," he warned.

Exchanges in India and China were closed down to prevent similar speculative attacks.

The global credit crunch also hamstrung government efforts to boost food production by reducing the money available for investment in new technology and better irrigation.

With climate change expected to reduce yields by 15% by 2050 even as demand grows from a rising world population, von Braum said it was important for nations and international institutions to respond with more funds for agriculture.

China, Japan, South Korea and several Middle Eastern nations have begun buying up farmland in Africa and South America as a hedge against food shortage risks.

Global prices are down from their peak thanks partly to effective measures by the Chinese government to rebuild grain stocks, increased agricultural investment in India and a great focus on food production in the aid programmes of the UK and other donor nations.

But von Braun said prices remain high in many African countries because of trade constraints and foreign exchange rates, while an unusually dry Indian monsoon could affect harvests in Asia. A UN report published earlier this week warned that Asia faces dire food shortages unless hundreds of billions of dollars are invested in better irrigation systems to grow crops for its growing population.

"Fundamentally, the crisis of high food prices in the majority of poor countries is not over at all," said von Braun.