Rising prices have sparked protests such as here in Pakistan

UN Secretary General Ban Ki-moon has urged nations to seize an "historic opportunity to revitalise agriculture" as a way of tackling the food crisis.

Mr Ban told a UN-sponsored summit in Rome that food production would have to rise by 50% by 2030 to meet demand.

Mr Ban said export restrictions and import tariffs ought to be minimised to alleviate the crisis.

The summit comes as food costs have reached a 30-year high in real terms, causing riots in many countries.

The host of the conference - the UN’s Food and Agriculture Organisation (FAO) - has warned the industrialised countries that unless they increase yields, eliminate barriers and move food to where it is needed most, a global catastrophe could result.

The recent crisis is believed to have pushed 100 million people into hunger worldwide.

Poorer countries are faced with a 40% increase in their food imports bill this year, and experts say some countries’ food bills have doubled in the past year.

Access problem

The taskforce Mr Ban created to target the food crisis is expected to present a 38-page report with measures that could cost up to $15bn (£7.5bn) to implement.

Beggar Thy Neighbour food policies cannot work - they only distort markets and force prices even higher Ban Ki-moon

Announcing some of its findings, Mr Ban said high food prices offered a chance to finally address the ongoing problem of access to food for the world’s poor.

"The threats are obvious to us all. Yet this crisis also presents us with an opportunity," he said.

"While we must respond immediately to high food prices, it is important that our longer term focus is on improving world food security," he said.

Measures to improve access to food for vulnerable people include expanding aid, boosting smallholder production and minimising export restriction and import tariffs, he added.

Mr Ban urged countries not to unilaterally intervene to control prices.

"Some countries have taken action by limiting exports or by imposing price controls," he said.

SUMMIT AGENDA Price controls, trade tariffs and export bans Subsidies for biofuels Help for farmers in poorer countries Effect of climate change on agriculture

"As I have said before, I say again now: Beggar Thy Neighbour food policies cannot work. They only distort markets and force prices even higher."

These measures should be accompanied simultaneously by action to ensure long-term resilience and global food security.

One area expected to generate disagreements in Rome is biofuel - most of the increase in maize production last year went into making fuels such as ethanol, not food.

UN officials said there would be a range of "confidence-building" options for governments.

Many observers have so far focused on Zimbabwe’s Robert Mugabe, whose presence at the summit has been called "obscene" by the UK and Australia.

Australian Foreign Minister Stephen Smith said the Zimbabwean president was "the person who has presided over the starvation of his people".