GENETIC modification and other biotechnologies are essential to increase food production and meet huge projected rises in the world's population, a leading expert on plant science has warned.

If the advances made in creating genetically modified foods are not used to increase food output the world could find itself in the grip of a food crisis in as little as 15 years, perhaps even ten, said Professor Mike Gale of the John Innes Centre, one of Europe's largest independent centres for research into plant and microbial science.

At present there are six billion people on the planet and, according to the United Nations, that number is set to rise to nine billion by 2050.

The current annual production of 1.8 billion tons of cereals must be increased to three billion tons a year, Prof Gale told the BioScience 2004 conference at Glasgow's SECC. He warned: "We have doubled food production over the past half century. Now we have to do it again, but this time we have to do it sustainably. We don't have any more good land and we don't have any more water and we have to use fewer chemicals.

"At least half of these increases will have to come from improved varieties, especially varieties bred to tolerate drought and salt and be resistant to pests and diseases. We must also reduce our reliance on fertilisers and other chemical inputs."

Biotechnology can both speed up the breeding process and provide crops with advantageous new genes, and genetic modification is one of a range of techniques available.

The technology can provide variations not otherwise available in the crop or close relatives - such as insect-resistant cowpeas for Africa, rice rich in vitamin A in Asia and disease-resistant bananas throughout the tropics.

Bananas are an exceptionally difficult crop to breed and those bought in most British supermarkets are derived from a breed produced about 100 years ago. Over that 100 years, they have become susceptible to a wide range of diseases, in particular the Black Sigatoka fungus. In Nigeria banana plants have to be sprayed about once a week with powerful fungicides. Advocates of genetic modification say many farmers in Africa lose their crops because they can not afford the fungicides.

Although Prof Gale acknowledges that genetic modification is not the only solution to breeding new varieties of crops, he is adamant that the potential benefits can be realised.

He said: "It is time we came out and said people do not die from GM and the way in which crops are bred. They die from lack of food. There are no risks from GM."

Despite GM trials in Britain concluding that two of the three crops tested had a damaging effect on wildlife, Prof Gale went on: "The results of the field trials carried out in this country are of absolutely no concern. If you look carefully at the trials it is evident that the GM crops required half of the herbicides compared to non-GM varieties, and also required half of the passes through the field by tractors. That means massive benefits to the environment."

Duncan McLaren, chief executive of Friends of the Earth Scotland, said: "People are dying because of the agriculture industry's obsession with hi-tech fixes like GM. Sustainable agricultural techniques and political solutions like land reform are driven off the agenda by the greed and arrogance of the biotechnology industries.

"What the companies are after is control over the food chain that doesn't actually deliver food for local people. The real issues in global food supply are about distribution of food and the way markets are undermined."