'The world needs to produce more food,' United Nations Secretary-General Ban Ki Moon told world leaders at the opening of a summit on the crisis here yesterday.

To head off mass starvation, he said food output must increase 50 per cent by 2030.

Lambasting 'trade and taxation policies that distort markets', he called for trade barriers to be lowered and export bans removed immediately.

Food prices have doubled in three years, according to the World Bank. Aid agencies say Japan and China have contributed to high rice prices by controlling their stocks.

'Nothing is more degrading than hunger, especially when man-made,' Mr Ban said.

The Rome-based UN Food and Agriculture Organisation is hosting the three-day summit to try to solve the short- term emergency of increased hunger caused by soaring prices. Already, an estimated 100 million people are being pushed into hunger.

'We have a historic opportunity to revitalise agriculture,' Mr Ban told some 50 heads of state and government.

'I call on you to take bold and urgent steps to address the root causes of this global food crisis.'

The summit will set the tone on food aid and subsidies for the Group of Eight summit in Japan next month and what is regarded as the concluding stages of the stalled talks under the World Trade Organisation (WTO) aimed at reducing trade distortions.

With food prices at a 30-year high, he warned that while the world must 'respond immediately', it must also put the long-term focus on 'improving food security'.

Japanese Prime Minister Yasuo Fukuda urged fellow world leaders to release excess stockpiles of food to ease shortages in poorer countries, offering more than 300,000 tonnes of imported rice held by Japan.

Mr Ban said a UN task force he set up to deal with the crisis is recommending the nations 'improve vulnerable people's access to food and take immediate steps to increase food availability in their communities'.

That means increasing food aid, supplying small farmers with seed and fertiliser in time for this year's planting seasons, and cutting trade restrictions to help the free flow of agricultural goods.

While pressures on the world's food supply are serious, they should not be exaggerated, the coordinator of the UN task force John Holmes said on the sidelines of the summit.

'We are not trying to say that millions of people are going to starve to death tomorrow...,' he said.

'We do need to act quickly both to meet these immediate needs and to start the longer-term process of re-investing in agriculture.'

REUTERS, AGENCE FRANCE-PRESSE, ASSOCIATED PRESS

GLOBAL CATASTROPHE IF FOOD RIOTS SPREAD