An international group of agriculture experts says global farming methods must change radically to better serve the poor and avoid an environmental collapse.

About 400 scientists issued the warning Tuesday in a report by the International Assessment of Agriculture Science and Technology for Development (IAASTD).

The experts say modern agricultural techniques have brought major increases in food production, but the benefits are unevenly spread.  They say an estimated 850 million people suffer from hunger worldwide, with 4 million joining their ranks annually.

The report also says farmers in many countries are poorly rewarded for their work and lack agricultural education and training.

The scientists say farming methods can be improved by combining higher productivity with protecting natural resources such as soils, water, forests and biodiversity.

The report was sponsored by the United Nations and the World Bank.  It warns that continuing with the current trends in food production and distribution will exhaust global resources and jeopardize the future of the world's children.

International aid organizations and food policy experts will meet in Rome on Wednesday to discuss how to tackle the underlying causes of world hunger. The conference is organized by relief groups CARE International and Oxfam.

U.N. Secretary-General Ban Ki-moon said Monday that global food crisis has reached emergency proportions. Food riots have erupted in more than 10 countries in Africa, Latin America and Asia in recent months.

Some information for this report was provided by AFP, AP and Reuters.